bug#29427: Problem sending emails in message-mode after restart

[Emmanuel Boudreault <emmanuel.boudreault@polymtl.ca>]

> After restarting emacs, message-mode tries to incorrectly guess the
> 'From' field of my e-mail even though it is already present.

I have found a workaround. When emacs calls sendmail, it passes along a
'-f' argument with a badly formed from address and that is my problem.
The from address is obtained using the 'message-sendmail-envelope-from'
function in 'message.el'..

I found a nice comment:

```
;; Always specify who from,
;; since some systems have broken sendmails.
;; But some systems are more broken with -f, so
;; we'll let users override this.
(and (null message-sendmail-f-is-evil)
  (list "-f" (message-sendmail-envelope-from)))
```

By setting 'message-sendmail-f-is-evil', I can bypass this bit of code
and everything works as expected. However, this is just a workaround
and doesn't correct the fact that emacs is reading the From field
incorrectly.

> Emmanuel - I am forwarding your email, which follows my
> signature, to the bug report's address.

Thank you, I forgot to hit reply all.


Cheers,
Emmanuel