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Re: replacing sanitizer w/ amavisd-new





--On Saturday, January 10, 2004 21:53 -0500 Dan MacNeil <omacneil@brave.cs.uml.edu> wrote:


Thanks for your reply.

Might I suggest MailScanner?

You might, some specific problems with amavisd-new that aren't present in
MailScanner  might be even more helpful.

At:
	 http://www.geocities.com/scottlhenderson/spamfilter.html

they say:

# mailscanner system, works with Postfix and other MTAs. This
uses unsupported methods to manipulate Postfix queue files, and there are
multiple reports of message duplication and/or delivery of truncated
messages.

It isn't exactly supported nor unsupported....Basically it relies on the fact that postfix can be told to use deferred transports on inbound, automatically forcing everything to go into the deferred queue. You run one copy of postfix in that mode. Another in a normal mode, minus smtp/incoming mail. I haven't had any problems with truncated email nor duplicate deliveries at all with recent-ish Postfix. MAilscanner monitors the deferred queue, pulling messages out of there and working on them, putting them into the inbound pickup area on the other postfix instance after processing. The sytem works well and is quick.

I don't see how postfix could be responsible for multiple deliveries in this scenario, nor how mailscanner would cause it. The only time that sort of thing would happen is for people who don't follow the instructions and don't put the three queues (mailscanner, inbound postfix, outbound postfix) on the same partition/filesystem. This is a MUST. mailscanner simply relinks the files into/out of work areas, this is fast, and atomic, assuming it's on the same filesystem. Otherwise if it's not the same filesystem you have to copy to/from staging areas to achieve the atomicity.


MailScanner catches about 30% more 'dangerous content' and virii than amavisd-new given the same virus scanner because MS seems to unpack more thoroughly/properly. MS supports/integrates the update system of all the virus scanners it supports negating the need to run a separate update cronjob all the time. MS supports throttles, amavisd does not, and so MS will be much nicer to an overloaded/very briskly loaded system than amavisd. amvisd requires copying the message multiple times, MS reduces this by using the link/unlink method that all mailservers use nowadays internally to their queues.

MS does require running two separate copies of postfix, that amavisd does not. There's a point for amavis. amavis eliminates unnecesary code from the resultant script at ./configure time, MailScanner doesn't. That said though MailScanner seems to work faster on my system.

Not sure how much else to go on about this.

--
Michael Loftis
Modwest Sr. Systems Administrator
Powerful, Affordable Web Hosting



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