Just lately, one of my courier servers has been getting into a bit of a pickle. In particular, we're getting hammered by so many incoming spam connections that we hit the (as configured) 40 process limit on SMTP. Unfortunately, some of these processes seem to hang open, and I'm not really sure why. This is on FC3 and Courier 0.50.0 (authlib 0.57).

I have RBL's enabled, so I see a good number of these get rejected on this check. I'm wondering if I might save myself some grief by adding affected source IP addresses into a reject list for SMTP so they aren't even allowed to connect, as a means of reducing the effect of these connections?

For now, I've simply bumped up the max process count a bit and am keeping a close eye on it to see whether the submit/emstpd process list starts growing larger than it should.

Any suggestions or pointers are appreciated. I am considering moving to the latest courier release on this system as well, just in case it might be related to any fixes made subsequent.