More out of curiosity than anything, I've been wondering if there are options for filtering outgoing SMTP. Not necessarily every single message, but a firewall-level tool to watch for a sudden burst in SMTP from one host, run some of the messages through SpamAssassin or the like, and trigger an alert if they rank highly for spam.
It seems like it's technologically possible, but I've never heard of anyone doing it, nor seen an actual implementation of it. Has anyone heard of this type of thing?
mhm ... i am using configserver mailscanner package for this. i've never been a wizz with mailservers on unix, so i preferred having this done by professionals. works like a charm, and saved a bunch of my time.