>I have an email receiving setup with one Postfix instance mapped to one >instance of Amavisd-new (spamassassin, ClamAV), > >Now to prepare for increasing traffic, I am looking on to scale out strategies >of my setup. > >So with that in mind, is it possible that one instance of Postfix can itself >distribute email load on two or more Amavisd-new instances spread over >different locations over the network >? > >In essence can postfix work as an SMTP load balancer ?
not load balancer, but (dumb) load distributor via DNS round-robin. My envelope-only-filter mx1 relays to cs.mydomain.net, a domain record set which has 3 IPs, one for each of our content-scanner boxes. I shown several times that DNS round-robin on an internal network like above sends splits the load to target IP +/- 2%. For intelligent load balancing, you could have a looping script that SMTP-connects to each IP in the target record set every minute, to remove a slow-responding IP from the record set with nsupdate, or to add an IP that returns to quick SMTP responding. Above, cs.mydomain.net would have to be defined as a dynamic zone with allow-update from the IP running the monitor script. Len
