Re: smtpmail-send-queued-mail fails with error 504 5.5.2

[Manuel Giraud via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

rameiko87@posteo.net writes:

>>> which should instead only be reserved for message-id's (as the
>>> description of this variable says. Does it happen somewhere else too?
>>> this is the second thing to fix).
>> How to fix something that we don't know about?
>
> Is there any way to check where the variable message-user-fqdn is
> being used?

Yes.  I've just used 'M-x rgrep' on Emacs lisp source.

> Also, I understand from your messages that when message-user-fqdn is
> nil then the Message-ID's are built with domain set to the value of
> the domain in user-mail-address, no matter whether this is a valid
> address or not.

Yes and it is a bit more complicated than that.  You can find the
precedence order for the chosen domain in 'message-make-fqdn' in
"message.el"

> In the preceding sentence, by domain I mean everything to the right of
> the at-sign. Is this correct?

Yes.

> When I set message-user-fqdn instead, are the Message-ID's always
> built by using the message-user-fqdn regardless of the value of
> user-mail-address?

Yes (likewise see 'message-make-fqdn').

> And then when message-user-fqdn is nil and user-mail-address is the
> default (that is user@fedora), then does Message Mode attempt sending
> to this invalid email address and shows an error, or does it modify
> the To: to some valid email address?

I guess you meant the "From:" here.  And, yes, as you can see in my
tests (and also yet again in 'message-make-fqdn'), it rewrites
"user@fedora" as "user@fedora.mail-host-address-is-not-set".
-- 
Manuel Giraud