421 Too many concurrent SMTP connections

[Brook]

I keep getting an email saying:

exim failed @ Sat Jan 31 05:04:58 2009. A restart was attempted automagically.
Service Check Method: [tcp connect]

Failure Reason: TCP Transaction Log:
<< 421 Too many concurrent SMTP connections; please try again later.
exim: ** [421 Too many concurrent SMTP connections; please try again later. != 220 ]

And sometimes when trying to send mail it fails with the same response.

I seem to be gtting some IPs with over 20 connections:

netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

Some of the connections are from UK ISPs, so could some of our clients have a virus sending out mail? (Most are from places like Turkey and eastern Europe though).

Any ideas what's going on? Is it safe to increase the number of connections allowed? If so how? And will that add loads to the server or pose any other risk?

Thanks in advance!

[JPC-Shaun]

Hi;

This error symptom happens most likely because of Exim service has been stopped in on the server. The service was restarted automatically by the chkservd daemon in cpanel.

You might want to sift through the log files in /var/log/maillog and /var/log/exim_mainlog. Also look under /var/log/clam-update.log.to see why it is crashing though.