mail delivery problems / MX record issue?

[Kevin Darcy]

Kevin Darcy wrote:

> nospam at home.com wrote:
>
> > On 5 Jun 2001 14:23:53 -0700, Kevin Darcy <kcd at daimlerchrysler.com>
> > wrote:
> >
> > >At the very least, they should be able to control what domains their mail
> > >server accepts mail for. Whether they can give a nicely-tailored rejection
> > >message on a per-domain basis, is another matter.
> >
> > Is it possible for a *NIX mail server not to accept mail for
> > particular users?
>
> Well, trivially, yes. If my mail server has no mailbox for user "foo", then I'll
> bounce mail sent to that mailbox. Now, if you mean, reject mail for particular
> users in *real-time* (i.e. as soon as you get the RCPT TO in the
> SMTP conversation), this is often not possible to do because the mail server is
> just a relay and doesn't have full knowledge of what mailboxes are valid and what
> aren't. Plus, even if it has that knowledge, this validity-checking could be
> quite resource-intensive (remember that a given SMTP message can have multiple
> RCPT TO's), and it might give spammers an efficient way to test the validity of
> their mailing lists. All in all, this feature is of dubious value and I doubt
> very many mail server packages implement it "out of the box".

Forget what I just said. _Traditionally_, mail servers will validate local mailboxes
in real time. Sigh. I've been dealing almost exclusively with relays for too long,
where such validation is impossible.

Now, let's get back on topic for the list...


- Kevin