[Mimedefang] Check if smtp server is alive

[David F. Skoll]

Bob Covell wrote:

> ----Question----
> What would be the best way to verify that the target mail server is alive
> and if not re-route it to a "backup" mail server?
> ----Scenario----

DNS.

Hold on before you object!!!

> Also, we are NOT wanting to perform the backup via dns.  We could have
> another MX with a higher weight but our goal is to have a non-published
> backup mail server.

You publish one MX record for your domain:

rolet.com   MX	1  canitbox.rolet.com

Your mailertable on the MIMEDefang box looks like this:

rolet.com	 esmtp:[back-end.rolet.com]

You then run a local nameserver on the MIMEDefang box that *only* the
MIMEDefang box uses.  You publish a private zone (visible only to
the MIMEDefang box) that looks like this:

back-end.rolet.com  MX	 1     preferred.back-end.rolet.com
back-end.rolet.com  MX	 10    backup.back-end.rolet.com

Presto!  Works like magic. :-)

(You don't need an actual private nameserver if you use bind 9.  You
can do the same thing with "views".)

Regards,

David.