Add support for django-anymail (ESP tags etc.)

[dokterbob]

Using django-anymail we could have emails automatically tagged with metadata (user id, submission id etc) and (later) provide feedback on email delivery, link clicking etc.

Suggestion: keep using Django's builtin EmailMessage but set anymail properties on it to discriminate submissions, newsletters and (potentially) users.

[gabn88]

This would be really handy I think! :+1:

[glanzel]

are there any news about this feature ?