Re: Mail transfer agent (debian-user-digest Digest V2020 #932)
On Wed 30 Sep 2020 at 23:26:20 -0500, David Wright wrote:
> On Sat 26 Sep 2020 at 10:50:11 (+0300), Andrei POPESCU wrote:
> > >
> > > It ought to—I have no idea whether mutt can even use it, though
> > > I suppose it's possible—but AIUI the file belongs to exim4-config.
> > > It "needs" a dot to prevent your being nagged about its lack, and
> > > having an @ in it could screw up any use exim makes of it.
> > > (I use it to set exim's HELO.) So I thought it best to mention it.
> >
> > As far as I recall[1] /etc/mailname is Debian specific[2], to be used by
> > all softwares (typically MTAs and some MUAs like mutt) that need a
> > domain part to construct a full e-mail address, when one isn't provided.
> >
> > [1] too lazy to check where it's documented, quite likely in Debian Policy
> > [2] as in Debian specific patches to support it
>
> Your ¹ is correct. Specifically, from
>
> file:///usr/share/doc/debian-policy/policy.html/ch-customized-programs.html#mail-transport-delivery-and-user-agents
>
> If your package needs to know what hostname to use on (for
> example) outgoing news and mail messages which are generated
> locally, you should use the file /etc/mailname. It will contain
> the portion after the username and @ (at) sign for email addresses
> of users on the machine (followed by a newline).
>
> Such a package should check for the existence of this file when it
> is being configured. If it exists, it should be used without
> comment, although an MTA’s configuration script may wish to prompt
> the user even if it finds that this file exists. If the file does
> not exist, the package should prompt the user for the value
> (preferably using debconf) and store it in /etc/mailname as well
> as using it in the package’s configuration. The prompt should make
> it clear that the name will not just be used by that package. For
> example, in this situation the inn package could say something
> like:
>
> Please enter the "mail name" of your system. This is the
> hostname portion of the address to be shown on outgoing news and
> mail messages. The default is syshostname, your system's host name.
>
> Mail name ["syshostname"]:
>
> where syshostname is the output of hostname --fqdn.
exim4 says:
The 'mail name' is the domain name used to 'qualify' mail addresses
without a domain name.
Sending to brian or cc'ing or bcc'ing brian would go to brian@axis.corp.
I interpret the above to apply to email addresses *only*. EHLO (HELO)
would not be involved.
> So on this system, its value is axis.corp, which you can see in the
> header of this email. It certainly shouldn't be an email address,
> containing a local part and @.
Correct. Users do do that; most of the time it hasn't any consequence
because they do not send to or cc brian. The complete address is used.
>
> I wasn't aware that there is a (somewhat old) wiki page which is
> supposed to list all the MTAs (which I understand as including
> programs which submit mail using SMTP) and how they interpret
> /etc/mailname. For some reason, mutt is treated under the heading
> for exim4. Half a dozen headings have no information listed, and
> I don't know whether there are packages/programs missing altogether.
I've always been aware of that page. The exim4 documentation is more
useful, however.
> There are at least three or four important fields that involve various
> interpretations of "from-ness": EHLO, envelope (MAIL_FROM), From:
> and Sender:. (That's ignoring Resent* and so on.) How these relate
> to each other is not straightforward, particularly for home users'
> machines, and their values can be an important factor in whether
> their emails make it into the Internet and on to their destination.
> What works for one person may not for another. (That's also
> ignoring intranet emails.)
exim4 gets the EHLO from /etc/hosts, not /etc/mailname.
--
Brian.
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