Todd Lyons said: > Dennis Peterson wanted us to know: > >>> Of the two processes (spam scanning and virus scanning), spam scanning >>> is >>> more resource-intensive (at least the way I do it) - so I virus scan >>> first, and spam-scan second. >>Interesting - that is exactly the opposite of my experiences so I'm >>interested in knowing more about your content scanning tool. I don't use >>Perl for this (or anything else) so I'm wondering if that may be a >> factor. > > Possibly. Using spamassassin in daemon mode with spamass-milter. > >>But yes, no point in double-damning a message when once will do, and I >>guess that was my point, and clearly the most efficient method should be >>first. > > When a milter is configured to reject at the SMTP level, it never gets > to the second milter in the chain. So if clamav-milter detects a virus, > the CPU intensive content scanning process never sees the message (hence > much lower load).
In the case of my systems I have but one milter that handles both spam and AV, and it's optimized to least-load priorities. It's also worth observing that as a consequence I have but one milter entry in sendmail.cf and one set of timeouts to fuss over, and I only mention it for any interested parties who are pondering over such things. > > The amount of time that clamav spends chomping on an email is typically > less than 1 second. The amount of time that spamassassin spends > chomping on an email is typically about 2 seconds. So ~33% time (or > less) for clamav and ~66% time (or more) for spamassassin. This > information gleaned from averages in my maillogs. A bit of background is helpful - in my environment we deal with huge image files as that is what we sell and receive, so we possibly are more large-attachment oriented than some businesses. I test both incoming and outgoing messages and attachments because I believe it is the most internet friendly policy, and that also runs up our server loads. I avoid some of that by scanning the content first. So as always, ymmv, batteries not included, cake will not be served, defend yourself at all times, yaddah yaddah. dp _______________________________________________ http://lurker.clamav.net/list/clamav-users.html
