I've been having an issue with version 10 where the unix.in service sits forever in a CLOSE_WAIT state:
# lsof -i:25 2>&1 | grep CLOSE_WAIT | wc -l
869
#
I was bit once with it where enough connections were opened to port 25 that went to CLOSE_WAIT that no more connections were allowed, thus, mail could not be received.
Anyone else seeing something like that?
--John