Distributed setup with realtime failover/balancing

[jonas at vrt.dk]

> This is over kill!
> 
> For inbound email:
> 
> 	mydomain.com IN MX 5 my.mail.server.mydomain.com
> 
> 
> 	my.mail.server.mydomain.com 2 IN A 1.2.3.4
> 	my.mail.server.mydomain.com 2 IN A 1.2.3.5
> 
> This works fine - causes the load balancing to be done a protocol level
> and in the event of a failure will automatically failover to the other
> box.  Worse case scenario is badly configured remote servers will wait
> for "retry interval" minutes before delivering to the other server.
> 
> 
Hmm well it might be overkill, but definitely not for the above reason. Your
describing the normal basic smtp loadbalancing/failover that mx records
provides, which is fine. The problem is in a mailscanner/mailwatch setup
there are more components than simply the smtp incbound traffic. After a
remote server have send a mail to either of the mx records, the mail is
stored temporary on one of the boxes, if that box goes down, that mail and
any mail quarantined on the box is unavailable to users. Which is not
acceptable.

Best regards
Jonas Larsen