Re: [Exim] receiver verify from a mail hub

On 2001-11-14 at 16:52 -0600, Todd Jagger wrote:
> mail hub. Basically if an email to "anyone@???" passes
> through their system they send a quick little smtp telnet to the
> specified machine, and if it doesn't return a 550 error the account is

"it" is actually ambiguous -- could be "RCPT TO" or "VRFY"; however
from the rest of the mail I suspect the former.

> created and the mail delivered. If it does get a 550 error the account
> is not created and the mail is also delivered to just bounce as normal.
>
> Because of this hub -> forwarder arrangement, however, all
> verifications are coming back positive. I really don't want to have
> them deliver to any other machine than the hub.
>
> Is there any simple way for me to set up Exim to send a 550 error for
> invalid addresses directly from the mail hub?
>
> Hope I've explained this properly....

If you have, and I'm understanding correctly, then your issue is that
for administrative simplicity, your hub knows nothing about local users
and just farms out the work to other servers. Now, for an external
service, you need your hub to know about local users.

If you don't have any infrastructure supporting knowledge of user
accounts, you're really stuck with having to pull in all the information
from the other servers, daily, and building lists of local users, and
some "no_verify" hackery on the director which actually maps the domains
out for remote delivery to the other hosts.

Really, this is an argument for things like LDAP, providing a master
database (replicated for stability) of users and information about them.
You can get by for now with some Perl/poison-of-choice scripting, but if
you have a lot of such domains and they're going to increase, and you're
having trouble keeping information about your users synchronised across
systems, you will probably find it worthwhile to read up on LDAP.
--
Learn from your parents' mistakes - use birth control!