Allow different MAIL TO and `To` headers

[Ethan Jucovy]

Currently the 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 To headers.

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.

[Ethan Jucovy]

add reference to this ticket number

[Ethan Jucovy]

Allow custom To headers

[anonymous]

+1. This would be useful for me too.

[Aymeric Augustin]

The patch looks good to me.

[Aymeric Augustin]

In [17293]:

Fixed #17444 -- Made it possible to customize the 'To' header in emails.