SA timeouts and unscanned mail.

[Pete]

I have found a message in my inbox this morning that does not appear in
the Maillogs at all, and does not contain ANY MailScanner header info. I
would have expected it to be detected as a Nigerian Scam email, but it
does not contain any marks from MailScanner.

The only inbound mail our system accepts is via MailScanners. There is
no other inbound path.

I have another messages that contains only the X-MSmail_priority header,
again i wqould have expected spam, but it appears to be unscanned.

Could this be related to heavr server load and SA timeouts, which is
something i am struggling with at the moment?

Is there a way to force MS NOT to deliver messages is SA timesout? I
would prefer the nmessage stayed in the MS queue until some free
resource allowed it to be processed? We have many mails being delivered
with SA time outs.