[Mimedefang] backup MX server & checking for valid users

[Nate Carlson]

On Wed, 14 May 2003, alan premselaar wrote:
> on the DMZ I have my primary MX server which does LDAP lookups to the
> active directory to reject uknown users at SMTP negotiation time. (so
> that way my postmaster mail doesn't get slammed with a bunch of "can't
> deliver to this non-existant email address" emails because of all the
> bunk virus/spam mails.

This a Sendmail server? Mind posting the relevant portions of your
.mc/mimedefang-filter?

> is there any way to configure sendmail and/or MD to do an SMTP
> user_exists type of check from the secondary MX server to the primary
> MX server? (making the assumption that if the primary MX server
> doesn't respond in $TIMEOUT that the mail will be accepted and queued)

Why not just have it check the LDAP server, too? That way you just rely on
the LDAP servers being up, instead of relying on your primary MX to be up.

Also better use of resources.. why make the Primary MX do the lookup when
you can do it directly?

-- 
Nate Carlson <natecars at real-time.com>   | Phone : (952)943-8700
http://www.real-time.com                | Fax   : (952)943-8500