diff --git a/.github/workflows/e2e-smoke-dev.yaml b/.github/workflows/e2e-smoke-dev.yaml
index c7a375a2..8fb541bc 100644
--- a/.github/workflows/e2e-smoke-dev.yaml
+++ b/.github/workflows/e2e-smoke-dev.yaml
@@ -26,7 +26,7 @@ jobs:
     # the real prod send path runs (outbox -> dispatch -> /api/transactional/send
     # -> audit), but with Datamailer's dry_run flag the render is returned inline
     # and nothing is delivered. For this to be SAFE, the dev DEPLOYMENT itself
-    # must run with DATAMAILER_TRANSACTIONAL_DRY_RUN=1 (set on the CMP dev ECS
+    # must run with RELAY_TRANSACTIONAL_DRY_RUN=1 (set on the CMP dev ECS
     # task definition, provisioned via Terraform in DataTalksClub/infra-terraform
     # -- it is not configured from this repo). Without it, dev would send real
     # email during the smoke run; the email tests xfail if no audit appears.
diff --git a/README.md b/README.md
index 657bc251..d6f435c8 100644
--- a/README.md
+++ b/README.md
@@ -194,30 +194,30 @@ Response:
 In local development, the version comes from the `VERSION` environment
 variable and falls back to `local-development-build-version-not-configured`.
 
-## Datamailer
+## Relay
 
-The platform can sync created users and course enrollments to Datamailer.
+The platform syncs users and course enrollments and sends email through Relay.
 
 Set all required environment variables to enable the integration:
 
 ```bash
-export DATAMAILER_URL="https://datamailer.dtcdev.click"
-export DATAMAILER_API_KEY="<token>"
-export DATAMAILER_CLIENT="dtc-courses"
-export DATAMAILER_AUDIENCE="dtc-courses"
-export DATAMAILER_FROM_EMAIL="courses"
+export RELAY_URL="https://relay.dtcdev.click"
+export RELAY_API_KEY="<token>"
+export RELAY_CLIENT="dtc-courses"
+export RELAY_AUDIENCE="dtc-courses"
+export RELAY_FROM_EMAIL="courses"
 ```
 
 Optional settings:
 
 ```bash
-export DATAMAILER_STRICT="0"
-export DATAMAILER_SYNC_ON_USER_CREATE="1"
+export RELAY_STRICT="0"
+export RELAY_SYNC_ON_USER_CREATE="1"
 ```
 
-With `DATAMAILER_STRICT=0`, Datamailer API failures are logged and don't
-break signup or enrollment flows. Set `DATAMAILER_STRICT=1` only when those
-flows should fail on Datamailer errors.
+With `RELAY_STRICT=0`, Relay API failures are logged and don't
+break signup or enrollment flows. Set `RELAY_STRICT=1` only when those
+flows should fail on Relay errors.
 
 `PUBLIC_BASE_URL` is used for links in delivered transactional email. Set it
 when sending email from a local server so messages contain public HTTPS links
@@ -230,17 +230,17 @@ export PUBLIC_BASE_URL="https://dev.courses.datatalks.club"
 ## Non-delivering email verification (dry run)
 
 To exercise the transactional email path without delivering anything, set
-`DATAMAILER_TRANSACTIONAL_DRY_RUN=1`. CMP then adds Datamailer's `dry_run` flag
+`RELAY_TRANSACTIONAL_DRY_RUN=1`. CMP then adds Relay's `dry_run` flag
 to every `POST /api/transactional/send`: the identical prod pipeline runs
-(outbox -> dispatch -> send -> `DatamailerSendAudit`), but Datamailer renders
+(outbox -> dispatch -> send -> `DatamailerSendAudit`), but Relay renders
 the email and returns it inline without sending, queuing, or persisting
-anything.
+anything. `DatamailerSendAudit` is retained as a historical database model name;
+it does not select or configure the old service.
 
 The rendered subject/bodies land in the audit's `response_payload["rendered"]`,
 which CMP exposes over HTTP at `GET /api/datamailer/send-audits`
 (filter by `email` / `template_key` / `idempotency_key`). The e2e smoke suite
-uses this to verify confirmation emails safely. This replaces the old local
-Datamailer capture/testbed compose stack.
+uses this to verify confirmation emails safely.
 
 Deadline reminder emails are triggered by a short CMP management command:
 
@@ -254,8 +254,8 @@ task. The recurring trigger (an EventBridge/CloudWatch rule targeting
 invocation role are provisioned via Terraform in `DataTalksClub/infra-terraform`,
 alongside the CMP ECS service. CMP doesn't configure the schedule.
 
-The scheduled task exits after reconciling Datamailer recipient lists and
-triggering Datamailer list sends. Datamailer handles per-recipient delivery
+The scheduled task exits after reconciling Relay recipient lists and
+triggering Relay list sends. Relay handles per-recipient delivery
 asynchronously.
 
 Every event is attempted even if an earlier one fails; each failure is written
@@ -268,16 +268,16 @@ curl -s -H "Authorization: Token $TOKEN" \
 ```
 
 Bulk sends post the whole recipient list inline, so they use a longer HTTP
-timeout than transactional sends (`DATAMAILER_TIMEOUT_SECONDS`, default 60).
-Don't lower it: hanging up mid-request makes Datamailer abandon the dispatch it
+timeout than transactional sends (`RELAY_TIMEOUT_SECONDS`, default 60).
+Don't lower it: hanging up mid-request makes Relay abandon the dispatch it
 is partway through, stranding every not-yet-sent message at `queued` with no
 error and no retry, while CMP records a failure for work that partly succeeded.
 
-Datamailer transactional template keys are stable code-level constants in CMP.
+Relay transactional template keys are stable code-level constants in CMP.
 Don't configure one environment variable per template.
 
-The CMP/Datamailer integration, including the conceptual design and API
-reference, is documented in
+The CMP/Relay integration, including the conceptual design and API reference,
+is documented in the historically named
 [`docs/datamailer-integration.md`](docs/datamailer-integration.md).
 
 ## API Data Access
diff --git a/accounts/tests_account_settings_base.py b/accounts/tests_account_settings_base.py
index 3cb65bd9..382152b0 100644
--- a/accounts/tests_account_settings_base.py
+++ b/accounts/tests_account_settings_base.py
@@ -1,12 +1,12 @@
 from django.test import override_settings
 
 from accounts.tests_base import (
-    DATAMAILER_DISABLED_SETTINGS,
+    RELAY_DISABLED_SETTINGS,
     AccountCourseTestCase,
 )
 
 
-@override_settings(**DATAMAILER_DISABLED_SETTINGS)
+@override_settings(**RELAY_DISABLED_SETTINGS)
 class AccountSettingsViewTestBase(AccountCourseTestCase):
     def account_settings_profile_payload(self):
         payload = {
diff --git a/accounts/tests_base.py b/accounts/tests_base.py
index c5c0ff79..bee0d64e 100644
--- a/accounts/tests_base.py
+++ b/accounts/tests_base.py
@@ -3,11 +3,11 @@
 from accounts.models import CustomUser
 from courses.models import Course, Enrollment
 
-DATAMAILER_DISABLED_SETTINGS = {
-    "DATAMAILER_URL": "",
-    "DATAMAILER_API_KEY": "",
-    "DATAMAILER_CLIENT": "",
-    "DATAMAILER_AUDIENCE": "",
+RELAY_DISABLED_SETTINGS = {
+    "RELAY_URL": "",
+    "RELAY_API_KEY": "",
+    "RELAY_CLIENT": "",
+    "RELAY_AUDIENCE": "",
 }
 
 
diff --git a/accounts/tests_email_preferences.py b/accounts/tests_email_preferences.py
index 91e8004d..48e46472 100644
--- a/accounts/tests_email_preferences.py
+++ b/accounts/tests_email_preferences.py
@@ -5,12 +5,12 @@
 
 from accounts.models import CustomUser
 from accounts.tests_base import (
-    DATAMAILER_DISABLED_SETTINGS,
+    RELAY_DISABLED_SETTINGS,
     AccountCourseTestCase,
 )
 
 
-@override_settings(**DATAMAILER_DISABLED_SETTINGS)
+@override_settings(**RELAY_DISABLED_SETTINGS)
 class AccountEmailPreferencesTestCase(AccountCourseTestCase):
     @patch(
         "accounts.views.email_preferences."
diff --git a/accounts/tests_enrollment_profile.py b/accounts/tests_enrollment_profile.py
index a52d4d40..4d842d72 100644
--- a/accounts/tests_enrollment_profile.py
+++ b/accounts/tests_enrollment_profile.py
@@ -2,12 +2,12 @@
 from django.urls import reverse
 
 from accounts.tests_base import (
-    DATAMAILER_DISABLED_SETTINGS,
+    RELAY_DISABLED_SETTINGS,
     AccountCourseTestCase,
 )
 
 
-@override_settings(**DATAMAILER_DISABLED_SETTINGS)
+@override_settings(**RELAY_DISABLED_SETTINGS)
 class EnrollmentProfileTestCase(AccountCourseTestCase):
     def enrollment_payload(self, display_public_profile=False):
         payload = {
diff --git a/accounts/tests_timezone.py b/accounts/tests_timezone.py
index cc0b9ba7..55c26aca 100644
--- a/accounts/tests_timezone.py
+++ b/accounts/tests_timezone.py
@@ -4,12 +4,12 @@
 from django.urls import reverse
 
 from accounts.tests_base import (
-    DATAMAILER_DISABLED_SETTINGS,
+    RELAY_DISABLED_SETTINGS,
     AccountCourseTestCase,
 )
 
 
-@override_settings(**DATAMAILER_DISABLED_SETTINGS)
+@override_settings(**RELAY_DISABLED_SETTINGS)
 class AccountTimezonePreferenceTestCase(AccountCourseTestCase):
     def post_timezone_preference(self, payload):
         url = reverse("update_timezone_preference")
diff --git a/api/openapi/data_paths.py b/api/openapi/data_paths.py
index 51fc8396..6bc26e82 100644
--- a/api/openapi/data_paths.py
+++ b/api/openapi/data_paths.py
@@ -151,18 +151,18 @@
 )
 COURSE_CERTIFICATES_OPERATION = operation(COURSE_CERTIFICATES_DATA)
 
-DATAMAILER_EVENTS_SUCCESS_RESPONSE = schema_response(
+RELAY_EVENTS_SUCCESS_RESPONSE = schema_response(
     "Datamailer event accepted",
     "DatamailerEventAccepted",
 )
-DATAMAILER_EVENTS_RESPONSES = {
-    "200": DATAMAILER_EVENTS_SUCCESS_RESPONSE,
+RELAY_EVENTS_RESPONSES = {
+    "200": RELAY_EVENTS_SUCCESS_RESPONSE,
     "400": INVALID_EVENT_PAYLOAD_RESPONSE,
     "401": INVALID_WEBHOOK_TOKEN_RESPONSE,
     "503": WEBHOOK_NOT_CONFIGURED_RESPONSE,
 }
-DATAMAILER_EVENTS_BODY = schema_request_body("DatamailerEvent")
-DATAMAILER_EVENTS_DESCRIPTION = (
+RELAY_EVENTS_BODY = schema_request_body("DatamailerEvent")
+RELAY_EVENTS_DESCRIPTION = (
     "Webhook used by Datamailer to report hard bounces, "
     "complaints, subscription changes, skipped/failed sends, and "
     "message lifecycle events back to CMP for support and audit "
@@ -171,25 +171,25 @@
     "configured Datamailer webhook token in the Authorization "
     "bearer token or X-Datamailer-Webhook-Token header."
 )
-DATAMAILER_EVENTS_DATA = OperationData(
+RELAY_EVENTS_DATA = OperationData(
     "api_datamailer_events",
     ["Datamailer"],
     "Receive Datamailer contact event",
-    DATAMAILER_EVENTS_RESPONSES,
-    body=DATAMAILER_EVENTS_BODY,
+    RELAY_EVENTS_RESPONSES,
+    body=RELAY_EVENTS_BODY,
     requires_auth=False,
-    description=DATAMAILER_EVENTS_DESCRIPTION,
+    description=RELAY_EVENTS_DESCRIPTION,
 )
-DATAMAILER_EVENTS_OPERATION = operation(DATAMAILER_EVENTS_DATA)
+RELAY_EVENTS_OPERATION = operation(RELAY_EVENTS_DATA)
 
-DATAMAILER_SEND_AUDITS_SUCCESS_RESPONSE = schema_response(
+RELAY_SEND_AUDITS_SUCCESS_RESPONSE = schema_response(
     "Datamailer send audits",
     "DatamailerSendAudits",
 )
-DATAMAILER_SEND_AUDITS_RESPONSES = {
-    "200": DATAMAILER_SEND_AUDITS_SUCCESS_RESPONSE,
+RELAY_SEND_AUDITS_RESPONSES = {
+    "200": RELAY_SEND_AUDITS_SUCCESS_RESPONSE,
 }
-DATAMAILER_SEND_AUDITS_PARAMETERS = [
+RELAY_SEND_AUDITS_PARAMETERS = [
     {
         "name": "email",
         "in": "query",
@@ -215,7 +215,7 @@
         "schema": {"type": "integer", "default": 25, "maximum": 100},
     },
 ]
-DATAMAILER_SEND_AUDITS_DESCRIPTION = (
+RELAY_SEND_AUDITS_DESCRIPTION = (
     "Lists CMP's own Datamailer send-audit rows (one per send attempt "
     "through the outbox -> dispatch -> /api/transactional/send pipeline). "
     "Each row's response_payload carries the message summary and, when the "
@@ -223,15 +223,15 @@
     "Used by the e2e smoke suite to verify the rendered email over HTTP "
     "without delivering anything. Ordered newest first."
 )
-DATAMAILER_SEND_AUDITS_DATA = OperationData(
+RELAY_SEND_AUDITS_DATA = OperationData(
     "api_datamailer_send_audits",
     ["Datamailer"],
     "List Datamailer send audits",
-    DATAMAILER_SEND_AUDITS_RESPONSES,
-    parameters=DATAMAILER_SEND_AUDITS_PARAMETERS,
-    description=DATAMAILER_SEND_AUDITS_DESCRIPTION,
+    RELAY_SEND_AUDITS_RESPONSES,
+    parameters=RELAY_SEND_AUDITS_PARAMETERS,
+    description=RELAY_SEND_AUDITS_DESCRIPTION,
 )
-DATAMAILER_SEND_AUDITS_OPERATION = operation(DATAMAILER_SEND_AUDITS_DATA)
+RELAY_SEND_AUDITS_OPERATION = operation(RELAY_SEND_AUDITS_DATA)
 
 DATA_PATHS_BY_URL_NAME = {
     "api_health": {
@@ -256,9 +256,9 @@
         "post": COURSE_CERTIFICATES_OPERATION,
     },
     "api_datamailer_events": {
-        "post": DATAMAILER_EVENTS_OPERATION,
+        "post": RELAY_EVENTS_OPERATION,
     },
     "api_datamailer_send_audits": {
-        "get": DATAMAILER_SEND_AUDITS_OPERATION,
+        "get": RELAY_SEND_AUDITS_OPERATION,
     },
 }
diff --git a/api/views/datamailer_webhook_validation.py b/api/views/datamailer_webhook_validation.py
index c4bf7197..007306f2 100644
--- a/api/views/datamailer_webhook_validation.py
+++ b/api/views/datamailer_webhook_validation.py
@@ -51,7 +51,7 @@ def bearer_token(request):
 
 
 def authenticate_webhook(request):
-    expected = getattr(settings, "DATAMAILER_WEBHOOK_TOKEN", "")
+    expected = getattr(settings, "RELAY_WEBHOOK_TOKEN", "")
     if not expected:
         return False
     token = bearer_token(request)
@@ -159,7 +159,7 @@ def load_webhook_fields(data):
 
 
 def validate_webhook_configuration(data):
-    webhook_token = getattr(settings, "DATAMAILER_WEBHOOK_TOKEN", "")
+    webhook_token = getattr(settings, "RELAY_WEBHOOK_TOKEN", "")
     if webhook_token:
         return None
     error = webhook_error(
diff --git a/cadmin/tests/campaign_view_base.py b/cadmin/tests/campaign_view_base.py
index b4da6abe..045a7a66 100644
--- a/cadmin/tests/campaign_view_base.py
+++ b/cadmin/tests/campaign_view_base.py
@@ -3,11 +3,11 @@
 from courses.models import Course, RegistrationCampaign, User
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
diff --git a/cadmin/tests/test_campaign_datamailer_views.py b/cadmin/tests/test_campaign_datamailer_views.py
index 9f28301e..b232c2be 100644
--- a/cadmin/tests/test_campaign_datamailer_views.py
+++ b/cadmin/tests/test_campaign_datamailer_views.py
@@ -4,7 +4,7 @@
 from django.urls import reverse
 
 from cadmin.tests.campaign_view_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     CampaignCadminViewBase,
     admin_credentials,
 )
@@ -12,7 +12,7 @@
 
 class CampaignDatamailerCadminViewTests(CampaignCadminViewBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
@@ -37,7 +37,7 @@ def test_campaign_edit_syncs_datamailer_campaign_draft(
         self.assertRedirects(response, url)
         self.assert_campaign_draft_upserted(upsert_campaign)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_campaigns.DatamailerCampaignClient.preview_campaign"
     )
@@ -71,7 +71,7 @@ def test_campaign_edit_previews_datamailer_campaign(
         self.assertContains(response, "Preview subject")
         self.assertContains(response, "Preview text")
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_campaigns.DatamailerCampaignClient.test_send_campaign"
     )
@@ -102,7 +102,7 @@ def test_campaign_edit_sends_datamailer_campaign_test(
             expected_recipients,
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_campaigns.DatamailerCampaignClient.queue_campaign"
     )
@@ -129,7 +129,7 @@ def test_campaign_edit_queues_datamailer_campaign(
             "cmp-registration-llm-zoomcamp"
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_campaigns.DatamailerCampaignClient.cancel_campaign"
     )
diff --git a/cadmin/views/campaign_datamailer.py b/cadmin/views/campaign_datamailer.py
index d4563f0f..4a9e868b 100644
--- a/cadmin/views/campaign_datamailer.py
+++ b/cadmin/views/campaign_datamailer.py
@@ -18,7 +18,7 @@
 )
 
 
-DATAMAILER_CAMPAIGN_UPSERT_ACTIONS = {
+RELAY_CAMPAIGN_UPSERT_ACTIONS = {
     "sync",
     "preview",
     "test_send",
@@ -132,7 +132,7 @@ def cancel_datamailer_campaign_action(request, client, external_key):
     return None, True
 
 
-DATAMAILER_CAMPAIGN_ACTION_HANDLERS = {
+RELAY_CAMPAIGN_ACTION_HANDLERS = {
     "sync": sync_datamailer_campaign_action,
     "preview": preview_datamailer_campaign_action,
     "test_send": test_send_datamailer_campaign_action,
@@ -142,7 +142,7 @@ def cancel_datamailer_campaign_action(request, client, external_key):
 
 
 def run_datamailer_campaign_action(data):
-    handler = DATAMAILER_CAMPAIGN_ACTION_HANDLERS.get(data.action)
+    handler = RELAY_CAMPAIGN_ACTION_HANDLERS.get(data.action)
     if handler:
         return handler(data.request, data.client, data.external_key)
 
@@ -151,7 +151,7 @@ def run_datamailer_campaign_action(data):
 
 
 def upsert_datamailer_campaign_if_needed(data):
-    if data.action not in DATAMAILER_CAMPAIGN_UPSERT_ACTIONS:
+    if data.action not in RELAY_CAMPAIGN_UPSERT_ACTIONS:
         return
 
     payload = registration_campaign_datamailer_payload(data.campaign)
diff --git a/cadmin/views/datamailer_operations.py b/cadmin/views/datamailer_operations.py
index 83ce75a5..d872aebf 100644
--- a/cadmin/views/datamailer_operations.py
+++ b/cadmin/views/datamailer_operations.py
@@ -17,7 +17,7 @@
 )
 
 
-DATAMAILER_RECIPIENT_LIST_KINDS = [
+RELAY_RECIPIENT_LIST_KINDS = [
     "registrations",
     "enrollments",
     "homework",
@@ -26,7 +26,7 @@
     "graduates",
 ]
 
-DATAMAILER_OPERATOR_COMMANDS = (
+RELAY_OPERATOR_COMMANDS = (
     {
         "title": "Bootstrap contacts",
         "description": "Load active CMP users into Datamailer contacts.",
@@ -96,6 +96,6 @@ def datamailer_operations_context():
         "send_by_status": send_by_status,
         "send_by_type": send_by_type,
         "recent_failed_sends": recent_failed_sends,
-        "operator_commands": DATAMAILER_OPERATOR_COMMANDS,
-        "recipient_list_kinds": DATAMAILER_RECIPIENT_LIST_KINDS,
+        "operator_commands": RELAY_OPERATOR_COMMANDS,
+        "recipient_list_kinds": RELAY_RECIPIENT_LIST_KINDS,
     }
diff --git a/course_management/datamailer/client.py b/course_management/datamailer/client.py
index c8a29c28..eed21b3c 100644
--- a/course_management/datamailer/client.py
+++ b/course_management/datamailer/client.py
@@ -16,7 +16,7 @@
 
 # Bulk sends post the whole recipient list inline, so they need far longer
 # than a single transactional message. This is not just a false-failure
-# problem: when we hang up early Datamailer abandons the dispatch it was
+# problem: when we hang up early Relay abandons the dispatch it was
 # midway through, and every message it had created but not yet sent stays
 # "queued" forever with no error and no retry. A July 2026 reminder run
 # delivered to exactly one recipient -- the first in the list -- and
@@ -37,22 +37,22 @@ class DatamailerConfig:
 
     @classmethod
     def from_settings(cls) -> "DatamailerConfig | None":
-        url = getattr(settings, "DATAMAILER_URL", "")
-        api_key = getattr(settings, "DATAMAILER_API_KEY", "")
-        client = getattr(settings, "DATAMAILER_CLIENT", "")
-        audience = getattr(settings, "DATAMAILER_AUDIENCE", "")
-        from_email = getattr(settings, "DATAMAILER_FROM_EMAIL", "")
+        url = getattr(settings, "RELAY_URL", "")
+        api_key = getattr(settings, "RELAY_API_KEY", "")
+        client = getattr(settings, "RELAY_CLIENT", "")
+        audience = getattr(settings, "RELAY_AUDIENCE", "")
+        from_email = getattr(settings, "RELAY_FROM_EMAIL", "")
 
         if not all([url, api_key, client, audience]):
             return None
 
-        strict = getattr(settings, "DATAMAILER_STRICT", False)
+        strict = getattr(settings, "RELAY_STRICT", False)
         transactional_dry_run = getattr(
-            settings, "DATAMAILER_TRANSACTIONAL_DRY_RUN", False
+            settings, "RELAY_TRANSACTIONAL_DRY_RUN", False
         )
         timeout = getattr(
             settings,
-            "DATAMAILER_TIMEOUT_SECONDS",
+            "RELAY_TIMEOUT_SECONDS",
             DEFAULT_TIMEOUT_SECONDS,
         )
         normalized_url = url.rstrip("/")
diff --git a/course_management/datamailer/recipient_list_imports.py b/course_management/datamailer/recipient_list_imports.py
index 7d38abc5..36be4391 100644
--- a/course_management/datamailer/recipient_list_imports.py
+++ b/course_management/datamailer/recipient_list_imports.py
@@ -38,7 +38,7 @@ def safe_s3_key_part(value):
 
 
 def import_object_key(kind, config, list_key, content_sha256):
-    import_prefix = getattr(settings, "DATAMAILER_IMPORT_S3_PREFIX", "")
+    import_prefix = getattr(settings, "RELAY_IMPORT_S3_PREFIX", "")
     safe_list_key = safe_s3_key_part(list_key)
     parts = [
         import_prefix,
@@ -58,17 +58,17 @@ def import_object_key(kind, config, list_key, content_sha256):
 
 
 def import_s3_bucket():
-    bucket = getattr(settings, "DATAMAILER_IMPORT_S3_BUCKET", "")
+    bucket = getattr(settings, "RELAY_IMPORT_S3_BUCKET", "")
     if not bucket:
         raise CommandError(
-            "DATAMAILER_IMPORT_S3_BUCKET must be set when using "
+            "RELAY_IMPORT_S3_BUCKET must be set when using "
             "--import-by-reference."
         )
     return bucket
 
 
 def import_s3_client():
-    region = getattr(settings, "DATAMAILER_IMPORT_S3_REGION", "")
+    region = getattr(settings, "RELAY_IMPORT_S3_REGION", "")
     s3_kwargs = {}
     if region:
         s3_kwargs["region_name"] = region
@@ -99,7 +99,7 @@ def upload_import_body(upload_body):
 def presigned_import_url(s3, bucket, key):
     params = {"Bucket": bucket, "Key": key}
     expires_in = getattr(
-        settings, "DATAMAILER_IMPORT_URL_EXPIRES_SECONDS", 3600
+        settings, "RELAY_IMPORT_URL_EXPIRES_SECONDS", 3600
     )
     return s3.generate_presigned_url(
         "get_object",
diff --git a/course_management/datamailer_outbox.py b/course_management/datamailer_outbox.py
index 2014d401..b78ab0b1 100644
--- a/course_management/datamailer_outbox.py
+++ b/course_management/datamailer_outbox.py
@@ -32,7 +32,7 @@ def enqueue_datamailer_outbox_event(
     should_dispatch = (
         data.dispatch_immediately
         if data.dispatch_immediately is not None
-        else getattr(settings, "DATAMAILER_OUTBOX_DISPATCH_IMMEDIATELY", False)
+        else getattr(settings, "RELAY_OUTBOX_DISPATCH_IMMEDIATELY", False)
     )
     event_uuid = uuid4()
     event_id = f"cmp-datamailer-event:{event_uuid}"
diff --git a/course_management/datamailer_outbox_senders.py b/course_management/datamailer_outbox_senders.py
index 9e9d1ae3..2b679c61 100644
--- a/course_management/datamailer_outbox_senders.py
+++ b/course_management/datamailer_outbox_senders.py
@@ -42,7 +42,7 @@ def send_contact_erase_event(client, payload):
     return client.contacts.erase_contact(email)
 
 
-DATAMAILER_OUTBOX_EVENT_SENDERS = {
+RELAY_OUTBOX_EVENT_SENDERS = {
     "recipient_list.member_upsert": send_recipient_list_member_upsert_event,
     "recipient_list.member_remove": send_recipient_list_member_remove_event,
     "recipient_list.members_bulk_upsert": (
@@ -53,7 +53,7 @@ def send_contact_erase_event(client, payload):
 
 
 def send_event(client, event_type: str, payload: dict[str, Any]):
-    sender = DATAMAILER_OUTBOX_EVENT_SENDERS.get(event_type)
+    sender = RELAY_OUTBOX_EVENT_SENDERS.get(event_type)
     if sender is None:
         raise ValueError(
             f"Unsupported Datamailer outbox event type: {event_type}"
diff --git a/course_management/datamailer_templates/README.md b/course_management/datamailer_templates/README.md
index bb7c1786..cbbfbc76 100644
--- a/course_management/datamailer_templates/README.md
+++ b/course_management/datamailer_templates/README.md
@@ -17,7 +17,7 @@ uv run python manage.py upsert_datamailer_templates --template-key peer-review-a
 ```
 
 This `PUT`s each template to Datamailer (`/api/transactional/templates/{key}`)
-using the `DATAMAILER_*` settings. View them at `<DATAMAILER_URL>/templates/`.
+using the `RELAY_*` settings. View them at `<RELAY_URL>/templates/`.
 
 ## What triggers each template
 
diff --git a/course_management/settings.py b/course_management/settings.py
index f41f746a..3cbf16ca 100644
--- a/course_management/settings.py
+++ b/course_management/settings.py
@@ -231,42 +231,42 @@ def env_list(name, default):
     os.getenv("AWS_REGION", os.getenv("AWS_DEFAULT_REGION", "")),
 )
 
-DATAMAILER_URL = os.getenv("DATAMAILER_URL", "")
-DATAMAILER_API_KEY = os.getenv("DATAMAILER_API_KEY", "")
-DATAMAILER_CLIENT = os.getenv("DATAMAILER_CLIENT", "")
-DATAMAILER_AUDIENCE = os.getenv("DATAMAILER_AUDIENCE", "")
-DATAMAILER_FROM_EMAIL = os.getenv("DATAMAILER_FROM_EMAIL", "")
-DATAMAILER_STRICT = os.getenv("DATAMAILER_STRICT", "0") == "1"
-DATAMAILER_TIMEOUT_SECONDS = float(
-    os.getenv("DATAMAILER_TIMEOUT_SECONDS", "60")
+RELAY_URL = os.getenv("RELAY_URL", "")
+RELAY_API_KEY = os.getenv("RELAY_API_KEY", "")
+RELAY_CLIENT = os.getenv("RELAY_CLIENT", "")
+RELAY_AUDIENCE = os.getenv("RELAY_AUDIENCE", "")
+RELAY_FROM_EMAIL = os.getenv("RELAY_FROM_EMAIL", "")
+RELAY_STRICT = os.getenv("RELAY_STRICT", "0") == "1"
+RELAY_TIMEOUT_SECONDS = float(
+    os.getenv("RELAY_TIMEOUT_SECONDS", "60")
 )
-# When enabled, transactional sends carry Datamailer's "dry_run" flag: the full
+# When enabled, transactional sends carry Relay's "dry_run" flag: the full
 # prod send path runs (outbox -> dispatch -> /api/transactional/send -> audit) but
-# Datamailer renders the email and returns it inline without delivering. Used by
+# Relay renders the email and returns it inline without delivering. Used by
 # the e2e smoke suite (and any non-delivering deployment) to mimic prod safely.
-DATAMAILER_TRANSACTIONAL_DRY_RUN = (
-    os.getenv("DATAMAILER_TRANSACTIONAL_DRY_RUN", "0") == "1"
+RELAY_TRANSACTIONAL_DRY_RUN = (
+    os.getenv("RELAY_TRANSACTIONAL_DRY_RUN", "0") == "1"
 )
-DATAMAILER_WEBHOOK_TOKEN = os.getenv("DATAMAILER_WEBHOOK_TOKEN", "")
-DATAMAILER_IMPORT_S3_BUCKET = os.getenv("DATAMAILER_IMPORT_S3_BUCKET", "")
-DATAMAILER_IMPORT_S3_PREFIX = os.getenv(
-    "DATAMAILER_IMPORT_S3_PREFIX", "datamailer-imports"
+RELAY_WEBHOOK_TOKEN = os.getenv("RELAY_WEBHOOK_TOKEN", "")
+RELAY_IMPORT_S3_BUCKET = os.getenv("RELAY_IMPORT_S3_BUCKET", "")
+RELAY_IMPORT_S3_PREFIX = os.getenv(
+    "RELAY_IMPORT_S3_PREFIX", "relay-imports"
 ).strip("/")
-DATAMAILER_IMPORT_URL_EXPIRES_SECONDS_VALUE = os.getenv(
-    "DATAMAILER_IMPORT_URL_EXPIRES_SECONDS", "3600"
+RELAY_IMPORT_URL_EXPIRES_SECONDS_VALUE = os.getenv(
+    "RELAY_IMPORT_URL_EXPIRES_SECONDS", "3600"
 )
-DATAMAILER_IMPORT_URL_EXPIRES_SECONDS = int(
-    DATAMAILER_IMPORT_URL_EXPIRES_SECONDS_VALUE
+RELAY_IMPORT_URL_EXPIRES_SECONDS = int(
+    RELAY_IMPORT_URL_EXPIRES_SECONDS_VALUE
 )
-DATAMAILER_IMPORT_S3_REGION = os.getenv("DATAMAILER_IMPORT_S3_REGION", "")
-DATAMAILER_SYNC_ON_USER_CREATE = (
-    os.getenv("DATAMAILER_SYNC_ON_USER_CREATE", "1") == "1"
+RELAY_IMPORT_S3_REGION = os.getenv("RELAY_IMPORT_S3_REGION", "")
+RELAY_SYNC_ON_USER_CREATE = (
+    os.getenv("RELAY_SYNC_ON_USER_CREATE", "1") == "1"
 )
 # Dispatch outbox events inline (True) or defer to the scheduled processor
 # (False, the production default). Tests set this to True so sync helpers fire
 # without an explicit process_due_datamailer_outbox call.
-DATAMAILER_OUTBOX_DISPATCH_IMMEDIATELY = (
-    os.getenv("DATAMAILER_OUTBOX_DISPATCH_IMMEDIATELY", "0") == "1"
+RELAY_OUTBOX_DISPATCH_IMMEDIATELY = (
+    os.getenv("RELAY_OUTBOX_DISPATCH_IMMEDIATELY", "0") == "1"
 )
 
 # Cache configuration
diff --git a/courses/management/commands/audit_datamailer_recipient_lists.py b/courses/management/commands/audit_datamailer_recipient_lists.py
index 8e5f6931..6c3ff3d6 100644
--- a/courses/management/commands/audit_datamailer_recipient_lists.py
+++ b/courses/management/commands/audit_datamailer_recipient_lists.py
@@ -96,8 +96,8 @@ def _datamailer_config(self):
         config = DatamailerConfig.from_settings()
         if config is None:
             raise CommandError(
-                "Datamailer is not configured. Set DATAMAILER_URL, "
-                "DATAMAILER_API_KEY, DATAMAILER_CLIENT, and DATAMAILER_AUDIENCE."
+                "Datamailer is not configured. Set RELAY_URL, "
+                "RELAY_API_KEY, RELAY_CLIENT, and RELAY_AUDIENCE."
         )
         return config
 
diff --git a/courses/management/commands/datamailer_campaign.py b/courses/management/commands/datamailer_campaign.py
index b6c1670d..2b38daba 100644
--- a/courses/management/commands/datamailer_campaign.py
+++ b/courses/management/commands/datamailer_campaign.py
@@ -174,8 +174,8 @@ def datamailer_config(self):
         config = DatamailerConfig.from_settings()
         if config is None:
             raise CommandError(
-                "Datamailer is not configured. Set DATAMAILER_URL, "
-                "DATAMAILER_API_KEY, DATAMAILER_CLIENT, and DATAMAILER_AUDIENCE."
+                "Datamailer is not configured. Set RELAY_URL, "
+                "RELAY_API_KEY, RELAY_CLIENT, and RELAY_AUDIENCE."
             )
         return config
 
diff --git a/courses/management/commands/datamailer_status.py b/courses/management/commands/datamailer_status.py
index 02389100..3b7f42e4 100644
--- a/courses/management/commands/datamailer_status.py
+++ b/courses/management/commands/datamailer_status.py
@@ -35,8 +35,8 @@ def add_arguments(self, parser):
     def handle(self, *args, **options):
         if not datamailer_enabled():
             raise CommandError(
-                "Datamailer is not configured. Set DATAMAILER_URL, "
-                "DATAMAILER_API_KEY, DATAMAILER_CLIENT, and DATAMAILER_AUDIENCE."
+                "Datamailer is not configured. Set RELAY_URL, "
+                "RELAY_API_KEY, RELAY_CLIENT, and RELAY_AUDIENCE."
             )
 
         writer = DatamailerStatusWriter(self.stdout)
diff --git a/courses/management/commands/send_deadline_reminders.py b/courses/management/commands/send_deadline_reminders.py
index 03d3f44e..d6c4a87a 100644
--- a/courses/management/commands/send_deadline_reminders.py
+++ b/courses/management/commands/send_deadline_reminders.py
@@ -36,8 +36,8 @@ def require_datamailer_config():
     config = DatamailerConfig.from_settings()
     if config is None:
         raise CommandError(
-            "Datamailer is not configured. Set DATAMAILER_URL, "
-            "DATAMAILER_API_KEY, DATAMAILER_CLIENT, and DATAMAILER_AUDIENCE."
+            "Datamailer is not configured. Set RELAY_URL, "
+            "RELAY_API_KEY, RELAY_CLIENT, and RELAY_AUDIENCE."
         )
     return config
 
diff --git a/courses/management/commands/sync_datamailer_contacts.py b/courses/management/commands/sync_datamailer_contacts.py
index 48248d8d..1738fbde 100644
--- a/courses/management/commands/sync_datamailer_contacts.py
+++ b/courses/management/commands/sync_datamailer_contacts.py
@@ -185,8 +185,8 @@ def get_datamailer_config(self):
         config = DatamailerConfig.from_settings()
         if config is None:
             raise CommandError(
-                "Datamailer is not configured. Set DATAMAILER_URL, "
-                "DATAMAILER_API_KEY, DATAMAILER_CLIENT, and DATAMAILER_AUDIENCE."
+                "Datamailer is not configured. Set RELAY_URL, "
+                "RELAY_API_KEY, RELAY_CLIENT, and RELAY_AUDIENCE."
             )
         return config
 
diff --git a/courses/management/commands/sync_datamailer_recipient_lists.py b/courses/management/commands/sync_datamailer_recipient_lists.py
index f2f37004..2880c52f 100644
--- a/courses/management/commands/sync_datamailer_recipient_lists.py
+++ b/courses/management/commands/sync_datamailer_recipient_lists.py
@@ -225,7 +225,7 @@ def get_datamailer_config(self):
         config = DatamailerConfig.from_settings()
         if config is None:
             raise CommandError(
-                "Datamailer is not configured. Set DATAMAILER_URL, "
-                "DATAMAILER_API_KEY, DATAMAILER_CLIENT, and DATAMAILER_AUDIENCE."
+                "Datamailer is not configured. Set RELAY_URL, "
+                "RELAY_API_KEY, RELAY_CLIENT, and RELAY_AUDIENCE."
         )
         return config
diff --git a/courses/management/commands/upsert_datamailer_templates.py b/courses/management/commands/upsert_datamailer_templates.py
index d25ac432..d528a7e5 100644
--- a/courses/management/commands/upsert_datamailer_templates.py
+++ b/courses/management/commands/upsert_datamailer_templates.py
@@ -71,8 +71,8 @@ def get_datamailer_config(self):
         config = DatamailerConfig.from_settings()
         if config is None:
             raise CommandError(
-                "Datamailer is not configured. Set DATAMAILER_URL, "
-                "DATAMAILER_API_KEY, DATAMAILER_CLIENT, and DATAMAILER_AUDIENCE."
+                "Datamailer is not configured. Set RELAY_URL, "
+                "RELAY_API_KEY, RELAY_CLIENT, and RELAY_AUDIENCE."
             )
         return config
 
diff --git a/courses/signals.py b/courses/signals.py
index ebd3fe90..585e8e1d 100644
--- a/courses/signals.py
+++ b/courses/signals.py
@@ -29,7 +29,7 @@ def sync_user_to_datamailer(sender, instance, created, **kwargs):
     if not created:
         return
 
-    if not getattr(settings, "DATAMAILER_SYNC_ON_USER_CREATE", True):
+    if not getattr(settings, "RELAY_SYNC_ON_USER_CREATE", True):
         return
 
     callback = partial(sync_contact, instance)
diff --git a/courses/tests/datamailer_contact_base.py b/courses/tests/datamailer_contact_base.py
index fe906239..ff4eee54 100644
--- a/courses/tests/datamailer_contact_base.py
+++ b/courses/tests/datamailer_contact_base.py
@@ -9,11 +9,11 @@
 from courses.models import Course
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
diff --git a/courses/tests/datamailer_homework_score_base.py b/courses/tests/datamailer_homework_score_base.py
index 89d39c09..9cf0e4f5 100644
--- a/courses/tests/datamailer_homework_score_base.py
+++ b/courses/tests/datamailer_homework_score_base.py
@@ -17,11 +17,11 @@
 from courses.models import Course, Enrollment, Homework, Submission
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
diff --git a/courses/tests/datamailer_membership_base.py b/courses/tests/datamailer_membership_base.py
index 495b919e..76e3960e 100644
--- a/courses/tests/datamailer_membership_base.py
+++ b/courses/tests/datamailer_membership_base.py
@@ -21,11 +21,11 @@
 )
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
@@ -37,7 +37,7 @@ class UpsertedRecipientMemberExpectation:
     list_type: str
 
 
-@override_settings(DATAMAILER_OUTBOX_DISPATCH_IMMEDIATELY=True)
+@override_settings(RELAY_OUTBOX_DISPATCH_IMMEDIATELY=True)
 class DatamailerMembershipBase(TestCase):
     def process_due_outbox(self):
         from course_management.datamailer_outbox_runs import (
diff --git a/courses/tests/datamailer_outbox_base.py b/courses/tests/datamailer_outbox_base.py
index 53481324..aecd98d2 100644
--- a/courses/tests/datamailer_outbox_base.py
+++ b/courses/tests/datamailer_outbox_base.py
@@ -21,15 +21,15 @@
 from courses.models import Course, Enrollment
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
-@override_settings(DATAMAILER_OUTBOX_DISPATCH_IMMEDIATELY=True, **DATAMAILER_SETTINGS)
+@override_settings(RELAY_OUTBOX_DISPATCH_IMMEDIATELY=True, **RELAY_SETTINGS)
 class DatamailerOutboxTestBase(TestCase):
     def http_error(self, status_code):
         exc = requests.HTTPError("request failed")
diff --git a/courses/tests/datamailer_project_score_base.py b/courses/tests/datamailer_project_score_base.py
index ee77110a..a752bf7f 100644
--- a/courses/tests/datamailer_project_score_base.py
+++ b/courses/tests/datamailer_project_score_base.py
@@ -22,11 +22,11 @@
 )
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
diff --git a/courses/tests/datamailer_recipient_lists_base.py b/courses/tests/datamailer_recipient_lists_base.py
index b2114e8f..3780c463 100644
--- a/courses/tests/datamailer_recipient_lists_base.py
+++ b/courses/tests/datamailer_recipient_lists_base.py
@@ -18,11 +18,11 @@
 )
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
diff --git a/courses/tests/datamailer_settings.py b/courses/tests/datamailer_settings.py
index 9c11463b..68ca8ec2 100644
--- a/courses/tests/datamailer_settings.py
+++ b/courses/tests/datamailer_settings.py
@@ -1,6 +1,6 @@
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
diff --git a/courses/tests/deadline_reminder_base.py b/courses/tests/deadline_reminder_base.py
index 2d2de77f..3aee834e 100644
--- a/courses/tests/deadline_reminder_base.py
+++ b/courses/tests/deadline_reminder_base.py
@@ -7,11 +7,11 @@
 from courses.models import Course, Enrollment
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
diff --git a/courses/tests/test_datamailer_campaign_command.py b/courses/tests/test_datamailer_campaign_command.py
index 9e08f188..3129ed73 100644
--- a/courses/tests/test_datamailer_campaign_command.py
+++ b/courses/tests/test_datamailer_campaign_command.py
@@ -8,11 +8,11 @@
 from django.test import TestCase, override_settings
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
@@ -104,7 +104,7 @@ def assert_campaign_actions_ran(self, expectation):
         )
         self.assertIn("queue: ok", command_output)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_datamailer_campaign_command_upserts_and_runs_actions(self):
         with (
             patch(
@@ -137,7 +137,7 @@ def test_datamailer_campaign_command_upserts_and_runs_actions(self):
         )
         self.assert_campaign_actions_ran(expectation)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_datamailer_campaign_command_requires_body(self):
         with self.assertRaisesMessage(
             CommandError,
@@ -153,7 +153,7 @@ def test_datamailer_campaign_command_requires_body(self):
                 *command_args,
             )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_datamailer_campaign_command_requires_category_tag(self):
         with self.assertRaisesMessage(CommandError, "--category-tag is required."):
             command_args = [
@@ -170,7 +170,7 @@ def test_datamailer_campaign_command_requires_category_tag(self):
                 *command_args,
             )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_datamailer_campaign_command_rejects_queue_and_cancel(self):
         with self.assertRaisesMessage(
             CommandError,
@@ -190,7 +190,7 @@ def test_datamailer_campaign_command_rejects_queue_and_cancel(self):
                 *command_args,
             )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("course_management.datamailer.client_campaigns.DatamailerCampaignClient.upsert_campaign")
     def test_datamailer_campaign_command_wraps_request_errors(
         self,
diff --git a/courses/tests/test_datamailer_certificates.py b/courses/tests/test_datamailer_certificates.py
index 089601c5..b3ebb1a8 100644
--- a/courses/tests/test_datamailer_certificates.py
+++ b/courses/tests/test_datamailer_certificates.py
@@ -16,11 +16,11 @@
 from courses.models import Course, Enrollment
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
@@ -151,8 +151,8 @@ def assert_course_graduate_recipient_payload(
 
 class DatamailerCertificatePayloadTestCase(TestCase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_FROM_EMAIL="courses",
+        **RELAY_SETTINGS,
+        RELAY_FROM_EMAIL="courses",
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     def test_certificate_availability_notification_payload(self):
@@ -165,7 +165,7 @@ def test_certificate_availability_notification_payload(self):
         assert_certificate_availability_payload(self, payload, enrollment)
 
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     def test_course_graduate_recipient_list_payload_targets_graduated_outcome(
@@ -186,7 +186,7 @@ def test_course_graduate_recipient_list_payload_targets_graduated_outcome(
 
 
 class DatamailerCertificateSendTestCase(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.send_transactional"
     )
@@ -214,7 +214,7 @@ def test_certificate_availability_notification_uses_datamailer_preference_catego
         bulk_upsert.assert_called_once()
         send.assert_called_once()
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.send_transactional"
     )
diff --git a/courses/tests/test_datamailer_client.py b/courses/tests/test_datamailer_client.py
index 4d4f21ae..864864f7 100644
--- a/courses/tests/test_datamailer_client.py
+++ b/courses/tests/test_datamailer_client.py
@@ -19,7 +19,7 @@
 class DatamailerClientEndpointTest(TestCase):
     def datamailer_config(self):
         return DatamailerConfig(
-            url="https://datamailer.example.com",
+            url="https://relay.example.com",
             api_key="secret-token",
             client="dtc-courses",
             audience="dtc-courses",
@@ -44,7 +44,7 @@ def assert_datamailer_request(self, expectation):
         }
         if expectation.params is not None:
             kwargs["params"] = expectation.params
-        expected_url = f"https://datamailer.example.com{expectation.path}"
+        expected_url = f"https://relay.example.com{expectation.path}"
         expectation.session.request.assert_called_once_with(
             expectation.method,
             expected_url,
@@ -82,14 +82,46 @@ def assert_datamailer_method_case(self, method_case):
 
     def test_missing_env_disables_datamailer(self):
         with override_settings(
-            DATAMAILER_URL="",
-            DATAMAILER_API_KEY="",
-            DATAMAILER_CLIENT="",
-            DATAMAILER_AUDIENCE="",
+            RELAY_URL="",
+            RELAY_API_KEY="",
+            RELAY_CLIENT="",
+            RELAY_AUDIENCE="",
         ):
             enabled = datamailer_enabled()
             self.assertFalse(enabled)
 
+    @override_settings(
+        RELAY_URL="https://relay.example.com",
+        RELAY_API_KEY="relay-token",
+        RELAY_CLIENT="dtc-courses",
+        RELAY_AUDIENCE="dtc-courses",
+        RELAY_FROM_EMAIL="courses",
+        RELAY_STRICT=True,
+    )
+    def test_relay_settings_configure_client(self):
+        config = DatamailerConfig.from_settings()
+
+        self.assertIsNotNone(config)
+        self.assertEqual(config.url, "https://relay.example.com")
+        self.assertEqual(config.api_key, "relay-token")
+        self.assertEqual(config.client, "dtc-courses")
+        self.assertEqual(config.audience, "dtc-courses")
+        self.assertEqual(config.from_email, "courses")
+        self.assertTrue(config.strict)
+
+    @override_settings(
+        RELAY_URL="",
+        RELAY_API_KEY="",
+        RELAY_CLIENT="",
+        RELAY_AUDIENCE="",
+        DATAMAILER_URL="https://datamailer.example.com",
+        DATAMAILER_API_KEY="legacy-token",
+        DATAMAILER_CLIENT="dtc-courses",
+        DATAMAILER_AUDIENCE="dtc-courses",
+    )
+    def test_legacy_datamailer_settings_do_not_configure_client(self):
+        self.assertFalse(datamailer_enabled())
+
     def test_client_methods_use_expected_endpoints_and_scope(self):
         cases = datamailer_method_cases()
         for case in cases:
diff --git a/courses/tests/test_datamailer_contact.py b/courses/tests/test_datamailer_contact.py
index 4c57ed4f..b15c2b6f 100644
--- a/courses/tests/test_datamailer_contact.py
+++ b/courses/tests/test_datamailer_contact.py
@@ -11,13 +11,13 @@
 from course_management.datamailer.sync.contacts import sync_contact
 from courses.models import Course
 from courses.tests.datamailer_contact_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerContactBase,
 )
 
 
 class DatamailerContactTest(DatamailerContactBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_contact_payload_includes_course_subscription_data(self):
         user, course = self.create_contact_payload_fixture()
 
@@ -38,7 +38,7 @@ def test_contact_tags_for_course_without_trailing_year(self):
         expected_tags.append("course-cohort-ml-zoomcamp")
         self.assertEqual(tags, expected_tags)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.upsert_contact"
     )
@@ -52,7 +52,7 @@ def test_sync_contact_logs_and_continues_on_api_failure(
 
         upsert.assert_called_once()
 
-    @override_settings(**DATAMAILER_SETTINGS, DATAMAILER_STRICT=True)
+    @override_settings(**RELAY_SETTINGS, RELAY_STRICT=True)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.upsert_contact"
     )
diff --git a/courses/tests/test_datamailer_contact_backfill.py b/courses/tests/test_datamailer_contact_backfill.py
index 9c3abfc9..b775ace3 100644
--- a/courses/tests/test_datamailer_contact_backfill.py
+++ b/courses/tests/test_datamailer_contact_backfill.py
@@ -6,13 +6,13 @@
 
 from accounts.models import CustomUser
 from courses.tests.datamailer_contact_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerContactBase,
 )
 
 
 class DatamailerContactBackfillTest(DatamailerContactBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.bulk_import_contacts"
     )
@@ -34,7 +34,7 @@ def test_contact_backfill_command_bulk_imports_users(
         self.assert_first_contact_import_payload(bulk_import)
         self.assert_contact_import_output(out)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.bulk_import_contacts"
     )
@@ -55,7 +55,7 @@ def test_contact_backfill_command_dry_run_does_not_call_datamailer(
         self.assertIn("Prepared 1 contact batch(es), 1 contact(s).", output)
         self.assertIn("batch 1: 1 contact(s)", output)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.bulk_import_contacts"
     )
diff --git a/courses/tests/test_datamailer_homework_score_send.py b/courses/tests/test_datamailer_homework_score_send.py
index 28b7b1e5..a005d3e1 100644
--- a/courses/tests/test_datamailer_homework_score_send.py
+++ b/courses/tests/test_datamailer_homework_score_send.py
@@ -13,7 +13,7 @@
     send_homework_score_notification,
 )
 from courses.tests.datamailer_homework_score_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerHomeworkScoreTestBase,
     HomeworkScoreListSendExpectation,
 )
@@ -22,7 +22,7 @@
 class DatamailerHomeworkScoreSendSuccessTest(
     DatamailerHomeworkScoreTestBase
 ):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListSendClient.send_to_list"
     )
@@ -63,7 +63,7 @@ def test_send_homework_score_notification_uses_list_send(
 class DatamailerHomeworkScoreSendFailureTest(
     DatamailerHomeworkScoreTestBase
 ):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListSendClient.send_to_list"
     )
diff --git a/courses/tests/test_datamailer_homework_scores.py b/courses/tests/test_datamailer_homework_scores.py
index fe845375..3cc3c6be 100644
--- a/courses/tests/test_datamailer_homework_scores.py
+++ b/courses/tests/test_datamailer_homework_scores.py
@@ -5,15 +5,15 @@
     homework_score_notification_payload,
 )
 from courses.tests.datamailer_homework_score_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerHomeworkScoreTestBase,
 )
 
 
 class DatamailerHomeworkScorePayloadTest(DatamailerHomeworkScoreTestBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_FROM_EMAIL="courses",
+        **RELAY_SETTINGS,
+        RELAY_FROM_EMAIL="courses",
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     def test_homework_score_notification_payload_targets_homework_submitters(
@@ -34,7 +34,7 @@ def test_homework_score_notification_payload_targets_homework_submitters(
         self.assert_homework_score_context_urls(payload)
         self.assert_homework_score_member(member, submission)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_homework_score_notification_payload_dedupes_student_submissions(
         self,
     ):
@@ -50,7 +50,7 @@ def test_homework_score_notification_payload_dedupes_student_submissions(
         self.assertEqual(member["email"], "learner@example.com")
         self.assertEqual(member["metadata"]["total_score"], 9)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_homework_score_notification_includes_submitters(self):
         homework = self.create_homework()
         user = self.create_user("learner@example.com")
diff --git a/courses/tests/test_datamailer_membership.py b/courses/tests/test_datamailer_membership.py
index 330f4abf..ff338d33 100644
--- a/courses/tests/test_datamailer_membership.py
+++ b/courses/tests/test_datamailer_membership.py
@@ -16,14 +16,14 @@
     sync_project_submission_to_datamailer,
 )
 from courses.tests.datamailer_membership_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerMembershipBase,
     UpsertedRecipientMemberExpectation,
 )
 
 
 class DatamailerMembershipTest(DatamailerMembershipBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_enrollment_recipient_list_payload_targets_course_enrolled(
         self,
     ):
@@ -54,7 +54,7 @@ def test_enrollment_recipient_list_payload_targets_course_enrolled(
             enrollment.pk,
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
@@ -84,7 +84,7 @@ def test_sync_enrollment_adds_contact_and_enrolled_member(
             f"user:{user.pk}",
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
@@ -115,7 +115,7 @@ def test_sync_homework_submission_adds_submitter_member(
         )
         self.assert_upserted_recipient_member(expectation)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
diff --git a/courses/tests/test_datamailer_membership_outcomes.py b/courses/tests/test_datamailer_membership_outcomes.py
index f2faab05..081bcc74 100644
--- a/courses/tests/test_datamailer_membership_outcomes.py
+++ b/courses/tests/test_datamailer_membership_outcomes.py
@@ -6,13 +6,13 @@
     sync_project_passed_outcome_to_datamailer,
 )
 from courses.tests.datamailer_membership_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerMembershipBase,
 )
 
 
 class DatamailerMembershipOutcomeTest(DatamailerMembershipBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
@@ -31,7 +31,7 @@ def test_sync_project_passed_outcome_upserts_passed_member(
         upsert_contact.assert_called_once()
         self.assert_project_passed_member_upserted(upsert_member, project)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.remove"
     )
diff --git a/courses/tests/test_datamailer_membership_removals.py b/courses/tests/test_datamailer_membership_removals.py
index 62332100..0d03bbea 100644
--- a/courses/tests/test_datamailer_membership_removals.py
+++ b/courses/tests/test_datamailer_membership_removals.py
@@ -8,14 +8,14 @@
     remove_project_submission_from_datamailer,
 )
 from courses.tests.datamailer_membership_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerMembershipBase,
 )
 
 
 class DatamailerMembershipRemovalTest(DatamailerMembershipBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
@@ -37,7 +37,7 @@ def test_remove_enrollment_removes_enrolled_and_graduate_members(
 
         self.assert_enrollment_members_removed(remove_member, course, enrollment)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.remove"
     )
@@ -60,7 +60,7 @@ def test_remove_homework_submission_deletes_submitter_member(
             submission,
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.remove"
     )
diff --git a/courses/tests/test_datamailer_outbox_contacts.py b/courses/tests/test_datamailer_outbox_contacts.py
index 085e2058..e00d3d77 100644
--- a/courses/tests/test_datamailer_outbox_contacts.py
+++ b/courses/tests/test_datamailer_outbox_contacts.py
@@ -8,13 +8,13 @@
     erase_contact_from_datamailer,
 )
 from courses.tests.datamailer_outbox_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerOutboxTestBase,
 )
 
 
 class DatamailerOutboxContactTest(DatamailerOutboxTestBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("course_management.datamailer.client_contacts.DatamailerContactClient.erase_contact")
     def test_erase_contact_enqueues_outbox_event(self, erase_contact):
         user = CustomUser.objects.create_user(
@@ -28,7 +28,7 @@ def test_erase_contact_enqueues_outbox_event(self, erase_contact):
         event = DatamailerOutboxEvent.objects.get()
         self.assert_erase_contact_outbox_event_for_user(event, user)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("course_management.datamailer.client_contacts.DatamailerContactClient.erase_contact")
     def test_erase_contact_enqueues_outbox_event_for_email(
         self, erase_contact
diff --git a/courses/tests/test_datamailer_outbox_memberships.py b/courses/tests/test_datamailer_outbox_memberships.py
index 3d950c33..a9427699 100644
--- a/courses/tests/test_datamailer_outbox_memberships.py
+++ b/courses/tests/test_datamailer_outbox_memberships.py
@@ -10,13 +10,13 @@
     sync_enrollment_to_datamailer,
 )
 from courses.tests.datamailer_outbox_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerOutboxTestBase,
 )
 
 
 class DatamailerOutboxMembershipTest(DatamailerOutboxTestBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
@@ -34,8 +34,8 @@ def test_membership_sync_failure_records_retryable_outbox_event(
 
 
 class DatamailerOutboxProcessingTest(DatamailerOutboxTestBase):
-    @override_settings(DATAMAILER_OUTBOX_DISPATCH_IMMEDIATELY=False)
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(RELAY_OUTBOX_DISPATCH_IMMEDIATELY=False)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
diff --git a/courses/tests/test_datamailer_outbox_status_commands.py b/courses/tests/test_datamailer_outbox_status_commands.py
index a75ec71b..8db6cd63 100644
--- a/courses/tests/test_datamailer_outbox_status_commands.py
+++ b/courses/tests/test_datamailer_outbox_status_commands.py
@@ -7,13 +7,13 @@
 from django.utils import timezone
 
 from courses.tests.datamailer_outbox_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerOutboxTestBase,
 )
 
 
 class DatamailerOutboxStatusCommandTest(DatamailerOutboxTestBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
diff --git a/courses/tests/test_datamailer_peer_review.py b/courses/tests/test_datamailer_peer_review.py
index cecf2ea9..e58bdfd0 100644
--- a/courses/tests/test_datamailer_peer_review.py
+++ b/courses/tests/test_datamailer_peer_review.py
@@ -29,11 +29,11 @@
 )
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
@@ -219,9 +219,9 @@ def assert_peer_review_send_audit(test_case):
 
 class DatamailerPeerReviewPayloadTest(TestCase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
-        DATAMAILER_FROM_EMAIL="courses",
+        RELAY_FROM_EMAIL="courses",
     )
     def test_peer_review_assignment_payload_includes_links_and_deadline(self):
         project = create_peer_review_assignment_fixture()
@@ -299,7 +299,7 @@ def test_preview_peer_review_email_prints_submission_previews(self):
 
 
 class DatamailerPeerReviewNotificationSendTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListSendClient.send_to_list"
     )
diff --git a/courses/tests/test_datamailer_preferences.py b/courses/tests/test_datamailer_preferences.py
index 4844b5b3..84dd6bdb 100644
--- a/courses/tests/test_datamailer_preferences.py
+++ b/courses/tests/test_datamailer_preferences.py
@@ -8,11 +8,11 @@
     update_email_preferences_for_user,
 )
 
-from .datamailer_settings import DATAMAILER_SETTINGS
+from .datamailer_settings import RELAY_SETTINGS
 
 
 class DatamailerPreferencesTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.contact_preferences"
     )
@@ -59,7 +59,7 @@ def test_get_email_preferences_for_user_reads_datamailer_categories(
             category_tags=category_tags,
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.update_contact_preferences"
     )
diff --git a/courses/tests/test_datamailer_project_outcomes.py b/courses/tests/test_datamailer_project_outcomes.py
index 80021eec..a3228e81 100644
--- a/courses/tests/test_datamailer_project_outcomes.py
+++ b/courses/tests/test_datamailer_project_outcomes.py
@@ -10,7 +10,7 @@
     send_project_score_notification,
 )
 from courses.tests.datamailer_project_score_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerProjectScoreTestBase,
     ProjectScoreListSendExpectation,
 )
@@ -18,7 +18,7 @@
 
 class DatamailerProjectOutcomeTest(DatamailerProjectScoreTestBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     def test_project_passed_recipient_list_payload_targets_passed_outcome(
@@ -48,7 +48,7 @@ def test_project_passed_recipient_list_payload_targets_passed_outcome(
         self.assertEqual(member["metadata"]["total_score"], 98)
         self.assertTrue(member["metadata"]["passed"])
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListSendClient.send_to_list"
     )
diff --git a/courses/tests/test_datamailer_project_scores.py b/courses/tests/test_datamailer_project_scores.py
index 6e1db486..f2828f83 100644
--- a/courses/tests/test_datamailer_project_scores.py
+++ b/courses/tests/test_datamailer_project_scores.py
@@ -5,7 +5,7 @@
     project_score_notification_payload,
 )
 from courses.tests.datamailer_project_score_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerProjectScoreTestBase,
     ScorePayloadExpectation,
 )
@@ -13,8 +13,8 @@
 
 class DatamailerProjectScoreTest(DatamailerProjectScoreTestBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_FROM_EMAIL="courses",
+        **RELAY_SETTINGS,
+        RELAY_FROM_EMAIL="courses",
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     def test_project_score_notification_payload_targets_project_submitters(
@@ -37,7 +37,7 @@ def test_project_score_notification_payload_targets_project_submitters(
         self.assert_project_score_context(payload)
         self.assert_project_score_member(member, submission)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_project_score_notification_dedupes_student_submissions(self):
         project, latest = self.create_duplicate_project_submissions()
 
@@ -49,7 +49,7 @@ def test_project_score_notification_dedupes_student_submissions(self):
             latest,
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_project_score_notification_includes_submitters(self):
         project, _ = self.create_project_score_submission()
 
diff --git a/courses/tests/test_datamailer_recipient_list_audit.py b/courses/tests/test_datamailer_recipient_list_audit.py
index 53da71ed..d227e4be 100644
--- a/courses/tests/test_datamailer_recipient_list_audit.py
+++ b/courses/tests/test_datamailer_recipient_list_audit.py
@@ -15,11 +15,11 @@
 from courses.models import Course, Enrollment
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
@@ -149,7 +149,7 @@ def assert_recipient_list_audit_repaired(test_case, expectation):
 
 
 class DatamailerRecipientListAuditNoDriftTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.reconcile"
     )
@@ -182,7 +182,7 @@ def test_recipient_list_audit_reports_no_drift(
 
 
 class DatamailerRecipientListAuditRepairTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.reconcile"
     )
@@ -214,7 +214,7 @@ def test_recipient_list_audit_can_repair_drift(
 
 
 class DatamailerRecipientListAuditListingErrorTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.list_members"
     )
@@ -236,7 +236,7 @@ def test_recipient_list_audit_rejects_truncated_member_listing(
                 extra_args=["--limit", "2"],
             )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.list_members"
     )
@@ -259,7 +259,7 @@ def test_recipient_list_audit_wraps_member_listing_errors(
 
 
 class DatamailerRecipientListAuditOptionValidationTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_recipient_list_audit_rejects_invalid_options(self):
         for args, message in (
             (
diff --git a/courses/tests/test_datamailer_recipient_list_imports.py b/courses/tests/test_datamailer_recipient_list_imports.py
index 90e34384..220b8f5b 100644
--- a/courses/tests/test_datamailer_recipient_list_imports.py
+++ b/courses/tests/test_datamailer_recipient_list_imports.py
@@ -7,7 +7,7 @@
 
 from course_management.datamailer.keys import course_enrolled_list_key
 from courses.tests.datamailer_recipient_lists_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerRecipientListCommandTestBase,
     ImportWaitExpectation,
 )
@@ -34,10 +34,10 @@ class DatamailerRecipientListImportCreationTest(
     DatamailerRecipientListCommandTestBase
 ):
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_IMPORT_S3_BUCKET="cmp-imports",
-        DATAMAILER_IMPORT_S3_PREFIX="datamailer-test",
-        DATAMAILER_IMPORT_URL_EXPIRES_SECONDS=900,
+        **RELAY_SETTINGS,
+        RELAY_IMPORT_S3_BUCKET="cmp-imports",
+        RELAY_IMPORT_S3_PREFIX="datamailer-test",
+        RELAY_IMPORT_URL_EXPIRES_SECONDS=900,
     )
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListImportClient.create"
@@ -83,8 +83,8 @@ class DatamailerRecipientListImportSuccessTest(
     DatamailerRecipientListCommandTestBase
 ):
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_IMPORT_S3_BUCKET="cmp-imports",
+        **RELAY_SETTINGS,
+        RELAY_IMPORT_S3_BUCKET="cmp-imports",
     )
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListImportClient.get"
@@ -129,8 +129,8 @@ class DatamailerRecipientListImportFailureTest(
     DatamailerRecipientListCommandTestBase
 ):
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_IMPORT_S3_BUCKET="cmp-imports",
+        **RELAY_SETTINGS,
+        RELAY_IMPORT_S3_BUCKET="cmp-imports",
     )
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListImportClient.get"
@@ -211,8 +211,8 @@ def assert_import_wait_times_out(self, enrollment, job_id):
                 )
 
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_IMPORT_S3_BUCKET="cmp-imports",
+        **RELAY_SETTINGS,
+        RELAY_IMPORT_S3_BUCKET="cmp-imports",
     )
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListImportClient.get"
@@ -241,7 +241,7 @@ def test_recipient_list_backfill_command_times_out_waiting_for_import(
 class DatamailerRecipientListImportValidationTest(
     DatamailerRecipientListCommandTestBase
 ):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_recipient_list_import_by_reference_requires_s3_bucket(self):
         self.create_registration(
             email="student@example.com",
@@ -250,7 +250,7 @@ def test_recipient_list_import_by_reference_requires_s3_bucket(self):
 
         with self.assertRaisesMessage(
             CommandError,
-            "DATAMAILER_IMPORT_S3_BUCKET must be set",
+            "RELAY_IMPORT_S3_BUCKET must be set",
         ):
             call_command(
                 "sync_datamailer_recipient_lists",
diff --git a/courses/tests/test_datamailer_recipient_lists.py b/courses/tests/test_datamailer_recipient_lists.py
index 8409ae13..d4afee9c 100644
--- a/courses/tests/test_datamailer_recipient_lists.py
+++ b/courses/tests/test_datamailer_recipient_lists.py
@@ -13,7 +13,7 @@
 )
 from courses.tests.datamailer_recipient_lists_base import (
     BulkUpsertMemberExpectation,
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerRecipientListCommandTestBase,
 )
 
@@ -27,7 +27,7 @@ def run_recipient_list_command(*args):
 class DatamailerRecipientListBulkUpsertTest(
     DatamailerRecipientListCommandTestBase
 ):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.bulk_upsert"
     )
@@ -55,7 +55,7 @@ def test_recipient_list_backfill_command_bulk_upserts_registrations(
         self.assert_bulk_upsert_member(expectation)
         self.assert_prepared_one_member(out)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.bulk_upsert"
     )
@@ -88,7 +88,7 @@ class DatamailerRecipientListProjectPassedTest(
     DatamailerRecipientListCommandTestBase
 ):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
@@ -153,7 +153,7 @@ class DatamailerRecipientListGraduateTest(
     DatamailerRecipientListCommandTestBase
 ):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
@@ -186,7 +186,7 @@ def test_recipient_list_backfill_command_bulk_upserts_graduates(
 class DatamailerRecipientListDryRunTest(
     DatamailerRecipientListCommandTestBase
 ):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.bulk_upsert"
     )
@@ -212,7 +212,7 @@ def test_recipient_list_backfill_command_dry_run_does_not_call_datamailer(
 class DatamailerRecipientListOptionValidationTest(
     DatamailerRecipientListCommandTestBase
 ):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     def test_recipient_list_backfill_command_rejects_invalid_options(self):
         for args, message in (
             (
diff --git a/courses/tests/test_datamailer_registration.py b/courses/tests/test_datamailer_registration.py
index 59975112..42091176 100644
--- a/courses/tests/test_datamailer_registration.py
+++ b/courses/tests/test_datamailer_registration.py
@@ -25,12 +25,12 @@
 )
 from courses.models import Course, CourseRegistration, RegistrationCampaign
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
-    "DATAMAILER_OUTBOX_DISPATCH_IMMEDIATELY": True,
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
+    "RELAY_OUTBOX_DISPATCH_IMMEDIATELY": True,
 }
 
 
@@ -230,7 +230,7 @@ def assert_registration_member_removed(
 
 class DatamailerRegistrationConfirmationPayloadTest(TestCase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     def test_registration_confirmation_payload(self):
@@ -243,7 +243,7 @@ def test_registration_confirmation_payload(self):
 
 class DatamailerRegistrationConfirmationSendTest(TestCase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
@@ -268,7 +268,7 @@ def test_send_registration_confirmation_email_uses_transactional_send(
 
 
 class DatamailerRegistrationMembershipSyncTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.upsert"
     )
@@ -290,7 +290,7 @@ def test_sync_registration_adds_contact_and_registrant_member(
 
 
 class DatamailerRegistrationMembershipRemovalTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListMemberClient.remove"
     )
diff --git a/courses/tests/test_datamailer_signals.py b/courses/tests/test_datamailer_signals.py
index 7a5292d2..5ed993ff 100644
--- a/courses/tests/test_datamailer_signals.py
+++ b/courses/tests/test_datamailer_signals.py
@@ -15,16 +15,16 @@
 )
 
 
-DATAMAILER_SETTINGS = {
-    "DATAMAILER_URL": "https://datamailer.example.com",
-    "DATAMAILER_API_KEY": "secret-token",
-    "DATAMAILER_CLIENT": "dtc-courses",
-    "DATAMAILER_AUDIENCE": "dtc-courses",
+RELAY_SETTINGS = {
+    "RELAY_URL": "https://relay.example.com",
+    "RELAY_API_KEY": "secret-token",
+    "RELAY_CLIENT": "dtc-courses",
+    "RELAY_AUDIENCE": "dtc-courses",
 }
 
 
 class DatamailerSignalTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.signals.sync_contact")
     def test_new_user_syncs_after_commit(self, sync):
         with self.captureOnCommitCallbacks(execute=True):
@@ -32,7 +32,7 @@ def test_new_user_syncs_after_commit(self, sync):
 
         sync.assert_called_once_with(user)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.signals.sync_enrollment_recipient_list")
     def test_new_enrollment_syncs_after_commit(self, sync):
         user = CustomUser.objects.create(email="student@example.com")
@@ -51,7 +51,7 @@ def test_new_enrollment_syncs_after_commit(self, sync):
 
         sync.assert_called_once_with(enrollment)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.signals.erase_contact_from_datamailer")
     def test_deleted_user_erases_contact_after_commit(self, erase_contact):
         user = CustomUser.objects.create_user(
@@ -68,7 +68,7 @@ def test_deleted_user_erases_contact_after_commit(self, erase_contact):
             email="student@example.com",
         )
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.signals.remove_registration_recipient_list")
     def test_deleted_registration_removes_member_after_commit(self, remove):
         course = Course.objects.create(
@@ -94,7 +94,7 @@ def test_deleted_registration_removes_member_after_commit(self, remove):
         remove.assert_called_once()
         self.assertEqual(remove.call_args.args[0].pk, registration.pk)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.signals.remove_enrollment_recipient_list")
     def test_deleted_enrollment_removes_member_after_commit(self, remove):
         user = CustomUser.objects.create(email="student@example.com")
@@ -112,7 +112,7 @@ def test_deleted_enrollment_removes_member_after_commit(self, remove):
         remove.assert_called_once()
         self.assertEqual(remove.call_args.args[0].pk, enrollment.pk)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.signals.remove_homework_submission_recipient_list")
     def test_deleted_homework_submission_removes_member_after_commit(
         self,
@@ -143,7 +143,7 @@ def test_deleted_homework_submission_removes_member_after_commit(
         remove.assert_called_once()
         self.assertEqual(remove.call_args.args[0].pk, submission.pk)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.signals.remove_project_submission_recipient_list")
     def test_deleted_project_submission_removes_member_after_commit(
         self,
diff --git a/courses/tests/test_datamailer_status.py b/courses/tests/test_datamailer_status.py
index a3e7d672..610cdc7b 100644
--- a/courses/tests/test_datamailer_status.py
+++ b/courses/tests/test_datamailer_status.py
@@ -4,7 +4,7 @@
 from django.core.management import call_command
 from django.test import TestCase, override_settings
 
-from .datamailer_settings import DATAMAILER_SETTINGS
+from .datamailer_settings import RELAY_SETTINGS
 
 
 def run_datamailer_status_command(*args):
@@ -14,7 +14,7 @@ def run_datamailer_status_command(*args):
 
 
 class DatamailerStatusCommandTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("courses.management.commands.datamailer_status.get_email_status")
     def test_datamailer_status_command_prints_email_history(
         self,
@@ -57,7 +57,7 @@ def test_datamailer_status_command_prints_email_history(
         self.assertIn("Recent campaign recipients:\n  none", output)
         get_status.assert_called_once_with("student@example.com", limit=10)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "courses.management.commands.datamailer_status."
         "get_transactional_message_status"
diff --git a/courses/tests/test_datamailer_sync_status.py b/courses/tests/test_datamailer_sync_status.py
index f6c474dd..0d3d4484 100644
--- a/courses/tests/test_datamailer_sync_status.py
+++ b/courses/tests/test_datamailer_sync_status.py
@@ -9,11 +9,11 @@
     get_transactional_message_status,
 )
 
-from .datamailer_settings import DATAMAILER_SETTINGS
+from .datamailer_settings import RELAY_SETTINGS
 
 
 class DatamailerContactSyncStatusTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.contact_status"
     )
@@ -27,7 +27,7 @@ def test_get_contact_status_uses_datamailer_client(
         self.assertEqual(result, {"exists": True})
         contact_status.assert_called_once_with("student@example.com")
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_contacts.DatamailerContactClient.contact_history"
     )
@@ -41,7 +41,7 @@ def test_get_contact_history_uses_datamailer_client(
         self.assertEqual(result, {"transactional_messages": []})
         contact_history.assert_called_once_with(42, limit=5)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch("course_management.datamailer.sync.status.get_contact_history")
     @patch("course_management.datamailer.sync.status.get_contact_status")
     def test_get_email_status_combines_status_and_history(
@@ -71,7 +71,7 @@ def test_get_email_status_combines_status_and_history(
         contact_history.assert_called_once_with(42, limit=5)
 
 class DatamailerMessageSyncStatusTest(TestCase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.transactional_message_status"
     )
diff --git a/courses/tests/test_datamailer_transactional.py b/courses/tests/test_datamailer_transactional.py
index 26afb0ef..93cda8b7 100644
--- a/courses/tests/test_datamailer_transactional.py
+++ b/courses/tests/test_datamailer_transactional.py
@@ -12,13 +12,13 @@
     send_transactional_email,
 )
 from courses.tests.datamailer_contact_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DatamailerContactBase,
 )
 
 
 class DatamailerTransactionalTest(DatamailerContactBase):
-    @override_settings(**DATAMAILER_SETTINGS, DATAMAILER_FROM_EMAIL="")
+    @override_settings(**RELAY_SETTINGS, RELAY_FROM_EMAIL="")
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.send_transactional"
     )
@@ -34,7 +34,7 @@ def test_send_transactional_email_uses_datamailer_client(
         self.assert_transactional_send_called(send)
         self.assert_transactional_send_audit()
 
-    @override_settings(**DATAMAILER_SETTINGS, DATAMAILER_FROM_EMAIL="")
+    @override_settings(**RELAY_SETTINGS, RELAY_FROM_EMAIL="")
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.send_transactional"
     )
@@ -53,8 +53,8 @@ def test_send_transactional_email_audits_api_failure(self, send):
         self.assertEqual(audit.error, "network error")
 
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_FROM_EMAIL="courses",
+        **RELAY_SETTINGS,
+        RELAY_FROM_EMAIL="courses",
     )
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.send_transactional"
@@ -80,8 +80,8 @@ def test_send_transactional_email_adds_configured_from_email(
         send.assert_called_once_with(expected_payload)
 
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_FROM_EMAIL="courses",
+        **RELAY_SETTINGS,
+        RELAY_FROM_EMAIL="courses",
     )
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.send_transactional"
@@ -108,9 +108,9 @@ def test_send_transactional_email_keeps_explicit_from_email(
         send.assert_called_once_with(expected_payload)
 
     @override_settings(
-        **DATAMAILER_SETTINGS,
-        DATAMAILER_FROM_EMAIL="courses",
-        DATAMAILER_TRANSACTIONAL_DRY_RUN=True,
+        **RELAY_SETTINGS,
+        RELAY_FROM_EMAIL="courses",
+        RELAY_TRANSACTIONAL_DRY_RUN=True,
     )
     @patch(
         "course_management.datamailer.client_transactional.DatamailerTransactionalClient.send_transactional"
diff --git a/courses/tests/test_deadline_reminder_dry_run.py b/courses/tests/test_deadline_reminder_dry_run.py
index b6b28f69..84cc9b02 100644
--- a/courses/tests/test_deadline_reminder_dry_run.py
+++ b/courses/tests/test_deadline_reminder_dry_run.py
@@ -6,13 +6,13 @@
 
 from courses.models import Homework
 from courses.tests.deadline_reminder_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DeadlineReminderTestBase,
 )
 
 
 class DeadlineReminderDryRunCommandTest(DeadlineReminderTestBase):
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(
         "course_management.datamailer.client_recipient_lists.DatamailerRecipientListSendClient.send_to_transient_list"
     )
diff --git a/courses/tests/test_deadline_reminder_failures.py b/courses/tests/test_deadline_reminder_failures.py
index f677a509..9e781cce 100644
--- a/courses/tests/test_deadline_reminder_failures.py
+++ b/courses/tests/test_deadline_reminder_failures.py
@@ -8,7 +8,7 @@
 
 from courses.models import Homework
 from courses.tests.deadline_reminder_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DeadlineReminderTestBase,
 )
 from data.models import DatamailerSendAudit, DatamailerSendAuditStatus
@@ -42,7 +42,7 @@ def create_two_homeworks(self, course, now):
         )
         return first, second
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(SEND_TARGET)
     def test_second_reminder_is_sent_when_first_one_fails(self, send_transient):
         now = self.reminder_run_time()
@@ -64,7 +64,7 @@ def test_second_reminder_is_sent_when_first_one_fails(self, send_transient):
         # Both events must have been attempted, not just the first.
         self.assertEqual(send_transient.call_count, 2)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(SEND_TARGET)
     def test_failure_is_reported_on_stderr_with_reason(self, send_transient):
         now = self.reminder_run_time()
@@ -89,7 +89,7 @@ def test_failure_is_reported_on_stderr_with_reason(self, send_transient):
         self.assertIn("homework-1", error_output)
         self.assertIn("timed out", error_output)
 
-    @override_settings(**DATAMAILER_SETTINGS)
+    @override_settings(**RELAY_SETTINGS)
     @patch(SEND_TARGET)
     def test_failed_send_records_error_on_audit(self, send_transient):
         now = self.reminder_run_time()
diff --git a/courses/tests/test_deadline_reminder_homework.py b/courses/tests/test_deadline_reminder_homework.py
index b71d9122..bf00f5e8 100644
--- a/courses/tests/test_deadline_reminder_homework.py
+++ b/courses/tests/test_deadline_reminder_homework.py
@@ -4,7 +4,7 @@
 from django.test import override_settings
 
 from courses.tests.deadline_reminder_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DeadlineReminderTestBase,
 )
 from courses.tests.deadline_reminder_homework import (
@@ -16,7 +16,7 @@
 
 class HomeworkDeadlineReminderCommandTest(DeadlineReminderTestBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
diff --git a/courses/tests/test_deadline_reminder_peer_review.py b/courses/tests/test_deadline_reminder_peer_review.py
index 47ff3a92..d52271d5 100644
--- a/courses/tests/test_deadline_reminder_peer_review.py
+++ b/courses/tests/test_deadline_reminder_peer_review.py
@@ -3,7 +3,7 @@
 from django.test import override_settings
 
 from courses.tests.deadline_reminder_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DeadlineReminderTestBase,
 )
 from courses.tests.deadline_reminder_peer_review import (
@@ -14,7 +14,7 @@
 
 class PeerReviewDeadlineReminderCommandTest(DeadlineReminderTestBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
diff --git a/courses/tests/test_deadline_reminder_project.py b/courses/tests/test_deadline_reminder_project.py
index 8d97b258..7dc15bab 100644
--- a/courses/tests/test_deadline_reminder_project.py
+++ b/courses/tests/test_deadline_reminder_project.py
@@ -3,7 +3,7 @@
 from django.test import override_settings
 
 from courses.tests.deadline_reminder_base import (
-    DATAMAILER_SETTINGS,
+    RELAY_SETTINGS,
     DeadlineReminderTestBase,
 )
 from courses.tests.deadline_reminder_project import (
@@ -14,7 +14,7 @@
 
 class ProjectSubmissionDeadlineReminderCommandTest(DeadlineReminderTestBase):
     @override_settings(
-        **DATAMAILER_SETTINGS,
+        **RELAY_SETTINGS,
         PUBLIC_BASE_URL="https://courses.example.com",
     )
     @patch(
diff --git a/courses/tests/test_registration_campaign_notifications.py b/courses/tests/test_registration_campaign_notifications.py
index 5a9a7d02..7584b696 100644
--- a/courses/tests/test_registration_campaign_notifications.py
+++ b/courses/tests/test_registration_campaign_notifications.py
@@ -8,10 +8,10 @@
 
 class RegistrationCampaignNotificationTests(RegistrationCampaignBase):
     @override_settings(
-        DATAMAILER_URL="https://datamailer.example.com",
-        DATAMAILER_API_KEY="secret-token",
-        DATAMAILER_CLIENT="dtc-courses",
-        DATAMAILER_AUDIENCE="dtc-courses",
+        RELAY_URL="https://relay.example.com",
+        RELAY_API_KEY="secret-token",
+        RELAY_CLIENT="dtc-courses",
+        RELAY_AUDIENCE="dtc-courses",
     )
     @patch(
         "courses.views.registration.send_registration_confirmation_email"
diff --git a/courses/tests/test_registration_campaigns.py b/courses/tests/test_registration_campaigns.py
index e2f15ab3..5241cb45 100644
--- a/courses/tests/test_registration_campaigns.py
+++ b/courses/tests/test_registration_campaigns.py
@@ -77,10 +77,10 @@ def test_registration_page_hides_count_when_no_signups(self):
         self.assertNotContains(response, "already registered")
 
     @override_settings(
-        DATAMAILER_URL="",
-        DATAMAILER_API_KEY="",
-        DATAMAILER_CLIENT="",
-        DATAMAILER_AUDIENCE="",
+        RELAY_URL="",
+        RELAY_API_KEY="",
+        RELAY_CLIENT="",
+        RELAY_AUDIENCE="",
     )
     def test_anonymous_registration_creates_independent_registration(
         self,
@@ -103,10 +103,10 @@ def test_anonymous_registration_creates_independent_registration(
         self.assertIsNone(registration.user)
 
     @override_settings(
-        DATAMAILER_URL="",
-        DATAMAILER_API_KEY="",
-        DATAMAILER_CLIENT="",
-        DATAMAILER_AUDIENCE="",
+        RELAY_URL="",
+        RELAY_API_KEY="",
+        RELAY_CLIENT="",
+        RELAY_AUDIENCE="",
     )
     def test_registration_stores_optional_company_name(self):
         url = self.campaign_url()
@@ -144,10 +144,10 @@ def test_duplicate_registration_shows_message(self):
         self.assertEqual(registration_count, 1)
 
     @override_settings(
-        DATAMAILER_URL="",
-        DATAMAILER_API_KEY="",
-        DATAMAILER_CLIENT="",
-        DATAMAILER_AUDIENCE="",
+        RELAY_URL="",
+        RELAY_API_KEY="",
+        RELAY_CLIENT="",
+        RELAY_AUDIENCE="",
     )
     def test_registration_requires_only_email_and_newsletter_consent(self):
         url = self.campaign_url()
@@ -218,10 +218,10 @@ def test_anonymous_registration_page_does_not_show_logout_link(self):
         self.assertNotContains(response, "to use a different email address")
 
     @override_settings(
-        DATAMAILER_URL="",
-        DATAMAILER_API_KEY="",
-        DATAMAILER_CLIENT="",
-        DATAMAILER_AUDIENCE="",
+        RELAY_URL="",
+        RELAY_API_KEY="",
+        RELAY_CLIENT="",
+        RELAY_AUDIENCE="",
     )
     def test_logged_in_registration_blank_optional_fields_keeps_profile(self):
         user = self.create_signed_blank_user()
diff --git a/data/tests/test_datamailer_callback_status.py b/data/tests/test_datamailer_callback_status.py
index 8be7b7cc..01d4fbef 100644
--- a/data/tests/test_datamailer_callback_status.py
+++ b/data/tests/test_datamailer_callback_status.py
@@ -7,7 +7,7 @@
 
 
 class DatamailerCallbackStatusCommandTest(DatamailerWebhookTestBase):
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_callback_status_command_reports_counts_and_duplicates(self):
         failed_payload = {
             "event_id": "evt-1",
diff --git a/data/tests/test_datamailer_webhook.py b/data/tests/test_datamailer_webhook.py
index 560981e7..191fc9ea 100644
--- a/data/tests/test_datamailer_webhook.py
+++ b/data/tests/test_datamailer_webhook.py
@@ -17,7 +17,7 @@ def test_webhook_requires_configured_token(self):
 
         self.assertEqual(response.status_code, 503)
 
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_rejects_invalid_token(self):
         payload = {
             "event_id": "evt-1",
@@ -31,7 +31,7 @@ def test_webhook_rejects_invalid_token(self):
 
 
 class DatamailerWebhookContactTest(DatamailerWebhookTestBase):
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_records_contact_event_idempotently(self):
         payload = {
             "event_id": "evt-1",
diff --git a/data/tests/test_datamailer_webhook_events.py b/data/tests/test_datamailer_webhook_events.py
index 87bba40d..78813132 100644
--- a/data/tests/test_datamailer_webhook_events.py
+++ b/data/tests/test_datamailer_webhook_events.py
@@ -6,7 +6,7 @@
 
 
 class DatamailerWebhookTransactionalEventTest(DatamailerWebhookTestBase):
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_records_transactional_failure_event(self):
         payload = {
             "event_id": "evt-tx-failed-1",
@@ -30,7 +30,7 @@ def test_webhook_records_transactional_failure_event(self):
             123,
         )
 
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_records_transactional_skipped_event(self):
         payload = {
             "event_id": "evt-tx-skipped-1",
@@ -47,7 +47,7 @@ def test_webhook_records_transactional_skipped_event(self):
 
 
 class DatamailerWebhookMessageEventTest(DatamailerWebhookTestBase):
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_records_message_lifecycle_event(self):
         payload = {
             "event_id": "evt-message-clicked-1",
diff --git a/data/tests/test_datamailer_webhook_preferences.py b/data/tests/test_datamailer_webhook_preferences.py
index 2eb46aaa..b59e1acc 100644
--- a/data/tests/test_datamailer_webhook_preferences.py
+++ b/data/tests/test_datamailer_webhook_preferences.py
@@ -8,7 +8,7 @@
 class DatamailerWebhookUnsubscribePreferenceTest(
     DatamailerWebhookTestBase,
 ):
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_unsubscribe_records_known_preference(self):
         user = self.create_student_user()
         payload = {
@@ -28,7 +28,7 @@ def test_webhook_unsubscribe_records_known_preference(self):
         event = DatamailerContactEvent.objects.get()
         self.assertEqual(event.preference_key, "email_deadline_reminders")
 
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_unsubscribe_records_preference_from_metadata(self):
         user = self.create_student_user()
         metadata = {
@@ -53,7 +53,7 @@ def test_webhook_unsubscribe_records_preference_from_metadata(self):
 
 
 class DatamailerWebhookUnsubscribeEventTest(DatamailerWebhookTestBase):
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_unsubscribe_without_preference_only_records_event(self):
         user = self.create_student_user()
         payload = {
@@ -74,7 +74,7 @@ def test_webhook_unsubscribe_without_preference_only_records_event(self):
 
 
 class DatamailerWebhookResubscribeTest(DatamailerWebhookTestBase):
-    @override_settings(DATAMAILER_WEBHOOK_TOKEN="secret-token")
+    @override_settings(RELAY_WEBHOOK_TOKEN="secret-token")
     def test_webhook_records_resubscribe_without_preference_change(self):
         user = self.create_student_user()
         payload = {
diff --git a/docs/datamailer-integration.md b/docs/datamailer-integration.md
index 1c795601..c5016561 100644
--- a/docs/datamailer-integration.md
+++ b/docs/datamailer-integration.md
@@ -1159,7 +1159,7 @@ as an operational safety net, but do not put reconcile back into every send.
 panel (§5) assumes a contact already exists with sane defaults. Target rules:
 
 - **Contact creation:** CMP creates/upserts a Datamailer contact on course
-  registration, account creation when `DATAMAILER_SYNC_ON_USER_CREATE=1`, and the
+  registration, account creation when `RELAY_SYNC_ON_USER_CREATE=1`, and the
   first enrollment/submission event if the contact does not already exist.
 - **Consent:** course registration remains the explicit newsletter / course email
   consent point. CMP sends `status: subscribed`, `verified: true`, and
@@ -1314,22 +1314,22 @@ Planned, not implemented yet:
 CMP enables Datamailer only when all required settings are present:
 
 ```text
-DATAMAILER_URL
-DATAMAILER_API_KEY
-DATAMAILER_CLIENT
-DATAMAILER_AUDIENCE
+RELAY_URL
+RELAY_API_KEY
+RELAY_CLIENT
+RELAY_AUDIENCE
 ```
 
 CMP may also set:
 
 ```text
-DATAMAILER_FROM_EMAIL
-DATAMAILER_STRICT
-DATAMAILER_WEBHOOK_TOKEN
-DATAMAILER_SYNC_ON_USER_CREATE
+RELAY_FROM_EMAIL
+RELAY_STRICT
+RELAY_WEBHOOK_TOKEN
+RELAY_SYNC_ON_USER_CREATE
 ```
 
-`DATAMAILER_FROM_EMAIL` is a Datamailer sender ID, not a raw email address.
+`RELAY_FROM_EMAIL` is a Datamailer sender ID, not a raw email address.
 Datamailer validates it against the authenticated client sender configuration.
 
 CMP keeps transactional template keys as code-level constants. We don't add one
@@ -1338,8 +1338,8 @@ environment variable per template.
 `PUBLIC_BASE_URL` is a CMP URL-building setting, not a Datamailer API setting.
 CMP uses it when it builds links for email context.
 
-When `DATAMAILER_STRICT=0`, CMP logs Datamailer failures and lets the course
-flow continue. When `DATAMAILER_STRICT=1`, CMP raises the Datamailer API failure
+When `RELAY_STRICT=0`, CMP logs Datamailer failures and lets the course
+flow continue. When `RELAY_STRICT=1`, CMP raises the Datamailer API failure
 to the caller.
 
 ### Where configuration lives — two sides
@@ -1353,7 +1353,7 @@ have **exactly one home**:
   address, the subscription **category tags** (§5), and — a strong candidate — the
   **link base host** (so templates compose `{{ base_url }}/{path}` and CMP never
   repeats it). Pinned here, an empty host is impossible.
-- **CMP-side — settings + per-send context.** Connection config (`DATAMAILER_URL`,
+- **CMP-side — settings + per-send context.** Connection config (`RELAY_URL`,
   `_API_KEY`, `_CLIENT`, `_AUDIENCE`), and the **per-message context** CMP computes:
   course title, slugs, scores, paths. If the base host is *not* a Datamailer
   client-global, then CMP pins `PUBLIC_BASE_URL` and sends fully-qualified URLs.
@@ -1498,7 +1498,7 @@ it upserts registrants into Datamailer.
 
 ```text
 POST /api/contacts
-Authorization: Bearer <DATAMAILER_API_KEY>
+Authorization: Bearer <RELAY_API_KEY>
 ```
 
 ```json
@@ -1544,7 +1544,7 @@ Single-recipient sends (submission confirmations, certificates):
 
 ```text
 POST /api/transactional/send
-Authorization: Bearer <DATAMAILER_API_KEY>
+Authorization: Bearer <RELAY_API_KEY>
 ```
 
 ```json
@@ -1581,7 +1581,7 @@ current computed audience. The send then names the node or transient list:
 
 ```text
 POST /api/recipient-lists/{list_key}/transactional-send
-Authorization: Bearer <DATAMAILER_API_KEY>
+Authorization: Bearer <RELAY_API_KEY>
 ```
 
 ```json
@@ -1667,7 +1667,7 @@ Rules:
 
 CMP verifies the transactional email path without delivering anything by using
 Datamailer's `dry_run` flag on `POST /api/transactional/send`. When
-`DATAMAILER_TRANSACTIONAL_DRY_RUN=1`, CMP adds `"dry_run": true` to every
+`RELAY_TRANSACTIONAL_DRY_RUN=1`, CMP adds `"dry_run": true` to every
 transactional send. Datamailer runs the **identical** validate/render pipeline
 (template lookup, context merge, required-field validation, category and
 suppression checks, render) and returns the rendered email inline **without**
@@ -1699,9 +1699,9 @@ curl -s -H "Authorization: Token $TOKEN" \
 ```
 
 For a local or CI end-to-end run, point CMP at a Datamailer deployment with
-normal settings (`DATAMAILER_URL`, `DATAMAILER_API_KEY`, `DATAMAILER_CLIENT`,
-`DATAMAILER_AUDIENCE`, `DATAMAILER_FROM_EMAIL`) and set
-`DATAMAILER_TRANSACTIONAL_DRY_RUN=1`. Use CMP normally (register, submit
+normal settings (`RELAY_URL`, `RELAY_API_KEY`, `RELAY_CLIENT`,
+`RELAY_AUDIENCE`, `RELAY_FROM_EMAIL`) and set
+`RELAY_TRANSACTIONAL_DRY_RUN=1`. Use CMP normally (register, submit
 homework, publish scores, and so on) and inspect the rendered results through
 `GET /api/datamailer/send-audits`.
 
@@ -1841,7 +1841,7 @@ For large lists, CMP can use Datamailer's file-by-reference import jobs instead
 of sending members inline:
 
 ```console
-DATAMAILER_IMPORT_S3_BUCKET=cmp-datamailer-imports \
+RELAY_IMPORT_S3_BUCKET=cmp-datamailer-imports \
   uv run python manage.py sync_datamailer_recipient_lists registrations \
     --course-slug ml-zoomcamp-2026 \
     --import-by-reference \
@@ -1980,7 +1980,7 @@ preferences (conceptually §5):
 
 ```text
 POST /api/datamailer/events
-Authorization: Bearer <DATAMAILER_WEBHOOK_TOKEN>
+Authorization: Bearer <RELAY_WEBHOOK_TOKEN>
 ```
 
 CMP stores each callback in `data_datamailercontactevent` keyed by Datamailer's
@@ -2089,7 +2089,7 @@ Target tests before relying on the integration:
   category/global-unsubscribe suppression decision, and link diagnostics for the
   same request, while the dry run never enqueues provider delivery.
 - **Local E2E dry-run tests:** run CMP against a Datamailer deployment with
-  `DATAMAILER_TRANSACTIONAL_DRY_RUN=1`. Use CMP normally to register, submit,
+  `RELAY_TRANSACTIONAL_DRY_RUN=1`. Use CMP normally to register, submit,
   publish scores, assign peer reviews, send deadline reminders, and publish
   certificates. Assert on the rendered text/HTML, suppression decisions, and
   links read back from `GET /api/datamailer/send-audits`.
diff --git a/e2e/README.md b/e2e/README.md
index cf3e62f2..1c4043d4 100644
--- a/e2e/README.md
+++ b/e2e/README.md
@@ -31,7 +31,7 @@ talks to the remote server over HTTP and a browser.
 | 3. Enrollment & identity (create/find student, impersonate, profile) | `tests/test_02_enrollment.py` | browser (loginas) |
 | 4. Homework flow (submit via UI, confirmation, score, leaderboard) | `tests/test_03_homework.py` | browser + API |
 | 5. Project flow (submit via UI, assign reviews, score, stats) | `tests/test_04_project.py` | browser + API |
-| 6. Email verification (homework + project confirmation emails) | `tests/test_03/04` (`@pytest.mark.email`) + `tests/test_06` (client unit tests) | CMP send audit (Datamailer dry-run render) |
+| 6. Email verification (homework + project confirmation emails) | `tests/test_03/04` (`@pytest.mark.email`) + `tests/test_06` (client unit tests) | CMP send audit (Relay dry-run render) |
 | 7. Dashboards & stats render | `tests/test_05_dashboards.py` | browser |
 | 8. Teardown + pre-run sweep + clean assert | `tests/test_99_teardown.py` | browser + API |
 
@@ -40,8 +40,8 @@ talks to the remote server over HTTP and a browser.
 Email checks mimic the production path but deliver nothing. CMP's real
 outbox → dispatch → `POST /api/transactional/send` → `DatamailerSendAudit`
 pipeline runs exactly as in prod, except the target deployment sets
-`DATAMAILER_TRANSACTIONAL_DRY_RUN=1`. CMP then adds Datamailer's `dry_run` flag
-to every transactional send: Datamailer runs the identical validate/render
+`RELAY_TRANSACTIONAL_DRY_RUN=1`. CMP then adds Relay's `dry_run` flag
+to every transactional send: Relay runs the identical validate/render
 pipeline and returns the rendered email inline **without** sending, queuing, or
 persisting anything.
 
@@ -64,8 +64,8 @@ context) contains `/homework/` / `/project/`.
 **What runs now vs. what's gated.** The client logic is covered by
 `tests/test_06_send_audit_client.py` (no-network unit tests — path, query
 params, response shape, poll/timeout, body matching). The **live** email
-assertions in `test_03/04` need the target deployment to have Datamailer
-configured **and** `DATAMAILER_TRANSACTIONAL_DRY_RUN=1`; when no matching audit
+assertions in `test_03/04` need the target deployment to have Relay
+configured **and** `RELAY_TRANSACTIONAL_DRY_RUN=1`; when no matching audit
 appears, they **xfail** (a fast pre-check avoids burning the poll timeout) so
 the suite stays green until dry-run is switched on.
 
diff --git a/e2e/api_client.py b/e2e/api_client.py
index b3d3d3b0..e5d0bd8d 100644
--- a/e2e/api_client.py
+++ b/e2e/api_client.py
@@ -355,7 +355,7 @@ def datamailer_send_audits(
 
         Mirrors the production email path: every send goes outbox -> dispatch
         -> ``/api/transactional/send`` -> ``DatamailerSendAudit``. With
-        ``DATAMAILER_TRANSACTIONAL_DRY_RUN=1`` on the target, the audit's
+        ``RELAY_TRANSACTIONAL_DRY_RUN=1`` on the target, the audit's
         ``response_payload`` carries the rendered subject/bodies without
         anything being delivered.
         """
@@ -415,7 +415,7 @@ def wait_for_send_audit(
             f"template_key={template_key!r} / body~={body_contains!r} within "
             f"{timeout}s. Seen: {[a.get('idempotency_key') for a in seen]!r}. "
             "Is Datamailer configured on the target with "
-            "DATAMAILER_TRANSACTIONAL_DRY_RUN=1?"
+            "RELAY_TRANSACTIONAL_DRY_RUN=1?"
         )
 
 
diff --git a/e2e/conftest.py b/e2e/conftest.py
index d2b87b39..4f78113d 100644
--- a/e2e/conftest.py
+++ b/e2e/conftest.py
@@ -67,7 +67,7 @@ def send_audits(api: CmpApiClient) -> CmpApiClient:
     Email verification no longer polls a mock/real inbox. Instead it reads
     CMP's ``DatamailerSendAudit`` rows over HTTP: the real prod path runs
     (outbox -> dispatch -> /api/transactional/send -> audit), but with
-    ``DATAMAILER_TRANSACTIONAL_DRY_RUN=1`` the render is returned inline and
+    ``RELAY_TRANSACTIONAL_DRY_RUN=1`` the render is returned inline and
     nothing is delivered. This fixture is the same ``CmpApiClient`` used for
     provisioning; it exposes ``datamailer_send_audits`` / ``wait_for_send_audit``.
     """
diff --git a/e2e/tests/test_03_homework.py b/e2e/tests/test_03_homework.py
index 47ab9848..c1366e90 100644
--- a/e2e/tests/test_03_homework.py
+++ b/e2e/tests/test_03_homework.py
@@ -154,7 +154,7 @@ def test_homework_confirmation_email(send_audits, run_state):
 
     Verification reads CMP's own ``DatamailerSendAudit`` over HTTP rather than
     an inbox: the prod path runs (outbox -> dispatch -> /api/transactional/send
-    -> audit), but with ``DATAMAILER_TRANSACTIONAL_DRY_RUN=1`` the render is
+    -> audit), but with ``RELAY_TRANSACTIONAL_DRY_RUN=1`` the render is
     returned inline and nothing is delivered. xfails cleanly when no audit
     appears (Datamailer not configured / dry-run off on the target), so the
     suite stays green until it is switched on.
@@ -170,7 +170,7 @@ def test_homework_confirmation_email(send_audits, run_state):
     except SendAuditTimeout as exc:
         pytest.xfail(
             "No homework-confirmation send audit found; ensure Datamailer is "
-            "configured on the target with DATAMAILER_TRANSACTIONAL_DRY_RUN=1. "
+            "configured on the target with RELAY_TRANSACTIONAL_DRY_RUN=1. "
             f"({exc})"
         )
     assert audit["template_key"] == HOMEWORK_CONFIRMATION_TEMPLATE
diff --git a/e2e/tests/test_04_project.py b/e2e/tests/test_04_project.py
index 868dd3c5..5c1c3b48 100644
--- a/e2e/tests/test_04_project.py
+++ b/e2e/tests/test_04_project.py
@@ -76,7 +76,7 @@ def test_project_confirmation_email(send_audits, run_state):
 
     Verification reads CMP's own ``DatamailerSendAudit`` over HTTP: the prod
     path runs (outbox -> dispatch -> /api/transactional/send -> audit) with
-    ``DATAMAILER_TRANSACTIONAL_DRY_RUN=1``, so the render is returned inline and
+    ``RELAY_TRANSACTIONAL_DRY_RUN=1``, so the render is returned inline and
     nothing is delivered. xfails cleanly when no audit appears.
     """
     require_project(run_state)
@@ -90,7 +90,7 @@ def test_project_confirmation_email(send_audits, run_state):
     except SendAuditTimeout as exc:
         pytest.xfail(
             "No project-confirmation send audit found; ensure Datamailer is "
-            "configured on the target with DATAMAILER_TRANSACTIONAL_DRY_RUN=1. "
+            "configured on the target with RELAY_TRANSACTIONAL_DRY_RUN=1. "
             f"({exc})"
         )
     assert audit["template_key"] == PROJECT_CONFIRMATION_TEMPLATE
diff --git a/e2e/tests/test_06_send_audit_client.py b/e2e/tests/test_06_send_audit_client.py
index 5eb89d6b..6b62854e 100644
--- a/e2e/tests/test_06_send_audit_client.py
+++ b/e2e/tests/test_06_send_audit_client.py
@@ -6,7 +6,7 @@
 targets (path, query params, auth header, response shape, poll/timeout, and the
 rendered-body matching used by the email tests). The *live* email assertions
 (``test_03/04``) still need a deployed dev target running with
-``DATAMAILER_TRANSACTIONAL_DRY_RUN=1``.
+``RELAY_TRANSACTIONAL_DRY_RUN=1``.
 """
 
 import json