bug#36937: 26.1; Sending mails doesn't set From: correctly

[Stefan Monnier]

Sven Joachim <svenjoac@gmx.de> writes:

> notfound 36937 26.1
> found 36937 27.0.50
> thanks
>
> On 2019-08-05 19:00 +0100, Jose A. Ortega Ruiz wrote:
>
>> This problem started happening in builds from master around 4 days ago:
>>
>> - start emacs -Q
>> - M-x mail (or any other form of sending email)
>> - Set a From: value different from user@localhostname
>> - Send mail using local sendmail
>>
>> The mail is sent with a from header seen by postfix (i don't know about
>> other MTAs) as user@localhost, instead of the From: i set in the
>> headers.  By user@localhost i mean the unix username running emacs and
>> the hostname as returned by hostname(1).  It seems emacs is just
>> ignoring the value of From:, or setting it in a way postfix doesn't
>> understand.
>>
>> I know almost for sure it's an emacs problem because emacs 26 or an
>> earlier version of emacs-snapshot is working without problems.
>
> Confirmed here, although it did not prevent me personally from sending
> mail, since I had already set up postfix to rewrite such
> user@localhostname addresses back.
>
> Reverting commit 3a59cc840693 (" * lisp/gnus/message.el: Reduce
> redundancy with send-mail-function") fixed the problem.  It looks like
> this commit changed some important options and looks NEWS-worthy.

It is not supposed to change anything important, so this is just a bug.

The weird thing is that `M-x mail` doesn't use message-mode, so it
should (in theory) be unaffected by my patch which only touches
message.el.  Practice proves the theory wrong, tho.


        Stefan