Load Balancing with Postfix [and SpamAssassin]

Alan Fullmer lists-alan at xnote.com
Wed Jan 18 14:34:22 MST 2006


I am wondering if anyone can direct me to any books/sites/etc regarding
possibly running postfix on one or more servers accepting mail, processing
with SA, then forwarding onto a 3rd machine.

Currently my setup only includes one Postfix box, which does all of the mail
filtering (with spamassassin) then forwards it on to a mailbox holding

The setup works, however I get so backlogged.  For example, running a mailq
as we speak, comes up with:
35918 Kbytes in 5257 Requests.

It eventually gets through, and during the night it catches up.  I am seeing
delays up to 3 hours sometimes.   I tail -f the maillog file and it's
constantly running, so there is definitely activity.   Running top indicates
4 main processes with spamd indicating the slowdown is, indeed, with
SpamAssassin.  I originally thought it might have something to do with the
Bayes database, but for fun, I deleted it to see what would happen.  Same

I am running a dual P3 1ghz machine currently and have plans to upgrade that
to a dual xeon 3ghz.  However, I know this is only a temporary solution and
at this point I'm not sure that it's enough.  

I get an enormous amount of mail coming into this machine and need to plan
accordingly for future growth as well.

So my goal is to possibly balance the incoming mail between two beefy
machines to do the processing, hopefully accomplishing and eliminating this
slow down.

My question is any suggestions on a different way to do this?  Or are there
suggestions on accomplishing a more balanced load between two machines.

Any comments, helpful hints or suggestions would be more than welcome.


Alan Fullmer

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