Allow different MAIL TO and `To` headers
|Reported by:||Ethan Jucovy||Owned by:||nobody|
|Cc:||Triage Stage:||Ready for checkin|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
EmailMessage.message method sets the email's
To: header to match the
to argument to the message object's constructor.
It can be useful to set a
To: header that is different from the actual recipients of the message. For example, when implementing a mailing list, the
To: header can be set to the mailing list's address itself.
Currently, however, if you pass a custom
To header in the constructor's
headers argument, the resulting message contains two
I've provided a patch with tests that will instead look for a custom
To header in
extra_headers when constructing the mail message, defaulting to the present behavior if no custom
To header was provided. This is analogous to the approach taken for the
From header, which was implemented in #9214.