Debugging and resolving high loadavg when running MailScanner

Richard Curtis richard at LEGENDJSM.CO.UK
Wed Feb 16 11:32:42 GMT 2005

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Hi All,
  I have been running MailScanner (Version 4.35.11) for some time, but
over the last 2 -3 weeks, my loadavg has gone from ~0.10-0.20 to as high
as 4.  This may not seem high to some, but as I have other services on
this box I want to try to reduce the load.
The box runs httpd, sendmail/MailScanner with clamav, radius and pop. 
There are multiple hosted domains on the server. 
The box is a dual AMD Athlon MP 1200 with 512MB RAM. 
All mail is scanned through MailScanner for virus's, but only a small
number of the domains (low traffic ones) have SpamAssassin enabled in
MailScanners configs.
I have to admit that I am a bit confused by some of the MailScanner
config options - for example, the effects of "Deliver In Background =
yes" and "Delivery Method = batch".
By setting the delivery method to queue, what kind of impact on delivery
time can I expect ?  Will this have a significant effect of lowering the
load ?
One other question, I note from looking through the logs, I see entries
Feb 16 11:25:32 lancelot MailScanner[7544]: New Batch: Scanning 1
messages, 1720 bytes
Feb 16 11:25:32 lancelot MailScanner[7544]: MCP Checks completed at 1720
bytes per second
Feb 16 11:25:32 lancelot MailScanner[7544]: Spam Checks completed at 1720
bytes per second
Now what confuses me here is that I have MCP checks and Spam checks set
to off for this mail domain - so why are the checks happening ?
Any suggestions on performance tuning of MailScanner, or possible
sendmail config tweaks would be greatly appreciated.

No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 14/02/05

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