Bulk course emails are rejected by email server because of an invalid "from" address

[regisb]

See this conversation: https://discuss.overhang.io/t/sending-bulk-email-triggers-smtprecipientsrefused-error/1923/10

When sending bulk course emails, by default the "from" address is built as follows: f"{courseid}-{bulk_email_from}". (source) In many cases, sender verification will fail for this address because it will not exist on the email server.

This is all the more surprising for the user, as they have properly defined the BULK_EMAIL_DEFAULT_FROM_EMAIL setting. A way to bypass this strange behaviour is to enable the EMAIL_USE_DEFAULT_FROM_FOR_BULK toggle -- but it's counter intuitive that we need to manually enable a toggle to use the "default" behaviour.

Thus, I propose the following changes:

1. Switch the EMAIL_USE_DEFAULT_FROM_FOR_BULK toggle default to True (i.e: rename EMAIL_USE_DEFAULT_FROM_FOR_BULK to EMAIL_USE_COURSE_ID_FROM_FOR_BULK).
2. When this toggle is True (EDIT: clarity) EMAIL_USE_COURSE_ID_FROM_FOR_BULK is False, the “from” address should default to settings.DEFAULT_FROM_EMAIL only if settings.BULK_EMAIL_DEFAULT_FROM_EMAIL is undefined. In other words:

if is_email_use_default_from_bulk_enabled():
    from_addr = settings.BULK_EMAIL_DEFAULT_FROM_EMAIL or settings.DEFAULT_FROM_EMAIL
else:
    ...

[Drakko25]

Hey @regisb I am looking at this issue. I've create the PR by now is a draft to check if the CI passes https://github.com/edx/edx-platform/pull/29001. Please let me know if any issues. Regards.

[regisb]

I realized by reading @Drakko25's PR that my proposed solution was unclear. I amended my initial post above. Let's talk further on edx/edx-platform#29001.

[BbrSofiane]

Needs to be merged in maple.master

[nizarmah]

@BbrSofiane I'd like to merge this into maple.master. cc @regisb

[nizarmah]

@regisb @BbrSofiane I created the backport PR to the maple master branch. Would either of you have time to review the pull request? Otherwise, do you have an idea who would be best to reach out to?

[regisb]

I realize that this issue still affects Lilac, but since it is resolved in Maple I'm closing this.

[nizarmah]

@regisb would you like me to create a backport pull request to lilac master, or is that not going to be necessary?

[regisb]

If you have time, that would be great but not strictly necessary, I guess, since we are 4 days away from the release.

[nizarmah]

@regisb the backport PR to lilac is ready for your review 😃