Mailscanner performance monitoring ?

[Arjan Melein]

We're currently getting flooded by spam and every so often our mailscanner is having trouble seems to have trouble keeping up causing our inbound queue to hit 3000+ messages and I am trying to figure out where the processing time is going.
I am getting the impression *something* is causing a delay, I am unsure as to what but I'm thinking in the way of RBL's or DNS...

The server is a quadcore with 20 MS threads and it can churn through 10-30 average mails per second depending on their size so either e-mails are being delivered faster then they can be scanned or there is indeed a delay somewhere.

Its a 'new' install (few months old) on FC18. I've seen it clear the 3000 message queue in 5 - 10 minutes after manually stopping and starting mailscanner.

Any ideas anyone ?

-
Arjan