Where I work I have implemented qpsmptd on our front-line mx servers in a quite geeky way. We currently we have 6 qpsmtpd boxes that pxe boot from a load balancer where they then mount there root directories from an iscsi san using oracles clustered file system. The biggest hurdle I've had to overcome with all of this is the ability to customize the scanning, whitelisting, blacklisting, and so forth for each domain we host on the fly. My result, a few custom modules that pull config information from a mysql database, whitelist/blacklist info from a database, and database based grey listing. I have also modified the denylog/maillog plugins to log directly to a mysql database for reporting and historical purposes. If anyone is interested in any of these modules just let me know and I'll throw them your way.
I want so send a thanks out to all of the developers that have work on qpsmtpd, it is by far one of the easiest to setup and use smtp servers out there and without my life would be hell. :) Ed.
