On Tue, Dec 09, 2003 at 09:38:34AM +0000, Tony Finch wrote:
> Russell King <rmk+exim@???> wrote:
> >My problem with IP literals is that (eg) postmaster@[myrelaymtaip] doesn't
> >exist in the first place. Note: I'm not saying that postmaster@mydomain
> >does not exist; it most certainly does. However, because the externally
> >reachable MTA purely provides filtering and routing with _zero_ local
> >users, it doesn't have a postmaster address of its own. It doesn't
> >even have any local domains as such. (It has a fixed set of domains
> >which it does relay for, and that's all.)
>
> Note that if Exim receives a message sent to <postmaster> (unqualified) it
> will use qualify_domain to turn it into a full email address. This address
> must work, and in fact it's hard to break it and still have working
> cron email etc. Once you notice this, it's easy to add a simple router
> to support postmaster-only machine-specific domains in the same way.
Correct, and of course, I've already checked that <postmaster> on its
own does indeed work as expected.
> Note that multi-homed machines, or machines whose reverse DNS differs from
> their primary hostname, should have all their aliases in the domain list.
That's debatable. Does it (or some other server) provide mail service
for those domains? If not, they aren't valid mail domains, so why
should postmaster@randomhostaddress be valid?
If you're going to say "well, it runs a SMTP server" what about a host
which only ever delivers mail, but never accepts mail?
There are these various side cases which need to be considered before
"postmaster@[randomip]" and "postmaster@randomreversedns" be expected
to work universally.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
