Mailscanner message delays / load issue

Alistair Carmichael Alistair.Carmichael at
Tue Jun 26 09:30:30 IST 2007



Over the past few months we have noticed a steady increase in the load
on our 2 mail scanner servers and in the last few days messages have
been substantially delayed between being collected from the inbound
mailqueue to the outbound mailqueue. We are running mailscanner  version
mailscanner-4.53.8-1 on centos running linux kernel 2.6.9-55 and using
sendmail 8.13 as the MTA and clamav as the anti-virus software and
spamassassin as the anti spam software.

We receive approximately 30,000 messages each day which are handled by a
cluster of 2 servers via DNS round robin, the load on both machines is
steadily at about 5,5,5 with clamscan processes constantly being at the
top of the process list in terms of cpu usage. We are also seeing log
entries similar to this constantly appearing in the maillog.

MailScanner[31171]: Commercial scanner clamav timed out!

MailScanner[31171]: Virus Scanning: Denial Of Service attack is in
message l5Q7bntD008994

Both servers are high powered machines only running the mailscanner
software (xeon 2.8 cpu and 2gb ram in each machine)

Is there a reason that the load would be so high as there's not a huge
quantity of email going through the servers for what I would expect them
to handle, or if there are any configuration tuning that can be done in
mailscanner to resolve this (we've fine tuned the time out settings in
sendmail to minimise message delays but this hasn't lowered the load or
message delivery time)


Thanks for any help



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