Ensure address validation is applied to all recipient headers

lib/mail.ex

@@ -430,8 +430,10 @@ defmodule Mail do
       iex> Mail.put_from(%Mail.Message{}, "[email protected]")
       %Mail.Message{headers: %{"from" => "[email protected]"}}
   """
-  def put_from(message, sender),
-    do: Mail.Message.put_header(message, "from", sender)
+  def put_from(message, sender) do
+    validate_recipients([sender])
+    Mail.Message.put_header(message, "from", sender)
+  end
 
   @doc ~S"""
   Retrieves the `from` header
@@ -485,9 +487,11 @@ defmodule Mail do
   defp validate_recipients([recipient | tail]) do
     case recipient do
       {name, address} when is_binary(name) and is_binary(address) ->
+        Mail.Renderers.RFC2822.validate_address(address)
         validate_recipients(tail)
 
       address when is_binary(address) ->
+        Mail.Renderers.RFC2822.validate_address(address)
         validate_recipients(tail)
 
       other ->

lib/mail/renderers/rfc_2822.ex

@@ -141,7 +141,9 @@ defmodule Mail.Renderers.RFC2822 do
   defp render_header_value(key, value),
     do: render_header_value(key, List.wrap(value))
 
-  defp validate_address(address) do
+  def validate_address(nil), do: raise(ArgumentError, message: "Email address cannot be nil")
+
+  def validate_address(address) do
     case Regex.match?(@email_validation_regex, address) do
       true ->
         address

test/mail/renderers/rfc_2822_test.exs

@@ -106,6 +106,31 @@ defmodule Mail.Renderers.RFC2822Test do
     assert header == "Bcc: [email protected], \"User 2\" <[email protected]>"
   end
 
+  ["to", "cc", "bcc", "from", "reply-to"]
+  |> Enum.each(fn header ->
+    test "validate address headers (#{header})" do
+      assert_raise ArgumentError, fn ->
+        Mail.Renderers.RFC2822.render_header(unquote(header), {"Test User", "@example.com"})
+      end
+
+      assert_raise ArgumentError, fn ->
+        Mail.Renderers.RFC2822.render_header(unquote(header), {"Test User", nil})
+      end
+
+      assert_raise ArgumentError, fn ->
+        Mail.Renderers.RFC2822.render_header(unquote(header), {"Test User", ""})
+      end
+
+      assert_raise ArgumentError, fn ->
+        Mail.Renderers.RFC2822.render_header(unquote(header), {"Test User", "user"})
+      end
+
+      assert_raise ArgumentError, fn ->
+        Mail.Renderers.RFC2822.render_header(unquote(header), {"Test User", nil})
+      end
+    end
+  end)
+
   test "content-transfer-encoding rendering hyphenates values" do
     header = Mail.Renderers.RFC2822.render_header("content_transfer_encoding", :quoted_printable)
     assert header == "Content-Transfer-Encoding: quoted-printable"

test/mail_test.exs

@@ -31,6 +31,16 @@ defmodule MailTest do
     assert Mail.get_to(mail) == ["[email protected]", "[email protected]"]
   end
 
+  test "put_to with invalid address" do
+    mail = Mail.build()
+
+    assert_raise ArgumentError, fn ->
+      Mail.put_to(mail, "@example.com")
+    end
+
+    refute Mail.Message.has_header?(mail, "to")
+  end
+
   test "composing multiple `to` recipients" do
     mail =
       Mail.put_to(Mail.build(), "[email protected]")
@@ -60,6 +70,16 @@ defmodule MailTest do
     assert Mail.get_cc(mail) == ["[email protected]", "[email protected]"]
   end
 
+  test "put_cc with invalid address" do
+    mail = Mail.build()
+
+    assert_raise ArgumentError, fn ->
+      Mail.put_cc(mail, "@example.com")
+    end
+
+    refute Mail.Message.has_header?(mail, "cc")
+  end
+
   test "composing multiple `cc` recipients" do
     mail =
       Mail.put_cc(Mail.build(), "[email protected]")
@@ -89,6 +109,16 @@ defmodule MailTest do
     assert Mail.get_bcc(mail) == ["[email protected]", "[email protected]"]
   end
 
+  test "put_bcc with invalid address" do
+    mail = Mail.build()
+
+    assert_raise ArgumentError, fn ->
+      Mail.put_bcc(mail, "@example.com")
+    end
+
+    refute Mail.Message.has_header?(mail, "bcc")
+  end
+
   test "composing multiple `bcc` recipients" do
     mail =
       Mail.put_bcc(Mail.build(), "[email protected]")