Too much spam

Too much spam

Postby wxPhil » Tue Jul 28, 2009 10:02 am

We've been runnin AMS for a couple of years now, or so, and been very pleased with its performance. During this time, we've been constantly training the Bayesian spam filter (at least, some of us have) and this, along with the other anti-spam features, have kept things manageable... however, the number of spam messages getting through the filters and ending up, unflagged, in the inbox seems to be increasing to silly levels now... Have we "over-trained" the Bayesian filter? Do we have to start again with that? (Sigh). Or is it just the sign of the times, and something we all have to put up with? Any tips?
Can we introduce the death penalty to spammers?
cheers
P
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Re: Too much spam

Postby Code Crafters » Tue Jul 28, 2009 10:07 am

It is possible that sometimes you're Bayesian can become poluted by being given the wrong emails for training by one of your users participating in the training. However, if given the correct emails for SPAM and non-SPAM training the Bayesian filter should just get stronger over time. Obviously though, new SPAM formats appear from time to time and when they do they might get through but if you keep sorting the mails into folders for training the Bayesian will auto-adjust to these in a relatively small amount of time, particularly if there are many of them. Our Bayesian is very well trained now and stops 99.5% of all our SPAM on its own. We get 500-1000 SPAM mails a day and rarely see one hit our Inbox. As for the other SPAM setup we recommend the following overall:

Basic Filtering:
1) Make sure you’re running the latest version.
2) Run the SPAM wizard from the dialog admin interface for medium level protection.
3) Set up any black / white listing that you need. The relaying exemption option will allow any authenticated users to bypass SPAM filtering.

Advanced Filtering:
4) If you want to also do Bayesian filtering, this take a bit of setting up but is by far the most effective SPAM filter available today.
a) Set up Bayesian filtering to use only the Auto-Learn from Users training method. Add participating users and appropriate SPAM / non-SPAM folders to the Bayesian settings.
b) Get Participating users to sort their mail into SPAM / non-SPAM folders where Bayesian will automatically learn from them periodically.
c) You need to disable rejecting (deleting) the email on all SPAM filters so that the SPAM flag is set and the mail is allowed to pass through.
d) Set up Content Filtering with the Preset Content Filter Rule (Add Preset button) “SPAM Identifier”. This rule will mark SPAM detected mails with <SPAM> in the subject so that they can be more easily identified and moved to the SPAM folder. Bayesian is a learning system so once it is well trained (minimum of 1000 SPAM and 1000 non-SPAM mails) you can set this content filter rule to also place mails in the SPAM account directory but don’t do this until you are happy it is training accurately and you must then check your SPAM folder for false positives (mails wrongly marked as SPAM that aren’t really SPAM) and move them appropriately.
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