Registration mail is not recieved by some e-mail providers like google mail

[jh-RLI]

Description of the issue

Users reported that they cannot sign up to the OEP as the registration conformation e-mail was never delivered to their inbox. This is especially true for google mail. Other provider received the mail in the SPAM inbox.

Ideas of solution

The e-mail backend used in django must be updated.

Context and Environment

• Version used:
• Operating system:
• Environment setup and (python) version:

Workflow checklist

• I am aware of the workflow in CONTRIBUTING.md