bug#56855: 27.1; sendmail-send-it considers it an error if sendmail wrote to stdout/stderr

[Lars Ingebrigtsen <larsi@gnus.org>]

Justus Winter <justus@sequoia-pgp.org> writes:

> In fact, I think we should ask what the best thing is for the user.  I
> think that (a) emacs should correctly indicate whether sending the mail
> succeeded or not, and (b) any warnings should be presented to the user.

Your argument makes sense, but there's a lot of systems out there, and
there's a lot of different things people use in place of
`sendmail-program'.  Emacs' contract with the user here has been (for 35
years) to consider any output from these programs as an error condition,
and changing that will inevitably lead to people losing mail, because
they're using that contract.

As a practical matter, accepting a SUCCESS exit code as a success, but
then showing the extra text isn't much friendlier than signalling an
error -- users don't want to see warnings every time they send a mail,
so they'll have to fix whatever program they're using for
`sendmail-program'.

So I think the fix here is to just document that output is considered
failure, and I've now done this in Emacs 29, and is therefore closing
this bug report.