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Learn Bayesian filter

Printed From: LogSat Software
Category: Spam Filter ISP
Forum Name: Spam Filter ISP Support
Forum Description: General support for Spam Filter ISP
URL: https://www.logsat.com/spamfilter/forums/forum_posts.asp?TID=4359
Printed Date: 22 February 2025 at 5:51pm


Topic: Learn Bayesian filter
Posted By: Guests
Subject: Learn Bayesian filter
Date Posted: 29 September 2004 at 3:40am

Hi.

Sorry for my bad English.

I have version 2.1.1.367. How I can learn bayesian filter by hand?


Replies:
Posted By: LogSat
Date Posted: 29 September 2004 at 10:58pm
Alexey,

In theory you could "inject" emails manually in SpamFilter to tweak the Bayesian filter, but that is usually a very bad idea. The Bayesian filter examines statistically the full email, headers included. Your artificial emails would not typically reflect the same content a true spam email will have. The headers may be different, if you copy and paste the content of an email from MS Outlook for example, the original source of the email will be very different since Microsoft Outlook completely changes the source, etc...

Roberto F. LogSat Software

Posted By: Guests
Date Posted: 30 September 2004 at 2:28am

Well, i (and not only me) CAN to feed SpamFilter source email (and i'm not using MS Outlook :-)). You are made Bayesian Probability on Bayesian Filter settings tab, why not to make, for example, check box that say filter that email is evident spam. Supplementary flexibility will only for good :-)

By the way, after 5000 spam and 5000 not spam emails, spam email will quarantined or rejected?

Posted By: LogSat
Date Posted: 30 September 2004 at 10:54pm
Alexey,

As I've stated, yes, you can inject emails if you want, but we do not feel it's usually a good idea. Bayesian filters are usually very accurate because the mathematics they are based on assume a real case scenario of text received. If you alter the real life by forcing certain tokens to receive a higher spam score, you risk altering the way a legitimate email is analyzed. If for example a legitimate email contains one of the tokens you artificially modified, the overall spam score assigned to it will not be accurate.

If however you feel confident that artificially altering some of the tokens will help the accuracy, you're absolutely free to try. Any email that SpamFilter processes is analyzed by the Bayesian engine. If you wish to inject tokens as spam, you can simply create an artificial email and for example change any of your blacklists so that it is blocked, which will cause the Bayesian filter to categorize the tokens as spam.

As far as your last question is concerned, mail blocked by the Bayesian filter will be quarantined if the quarantine database is configured, otherwise it will be rejected.

Roberto F. LogSat Software

Posted By: Guests
Date Posted: 01 October 2004 at 2:12am

Roberto,

I see. Why i bother with this questions? By default, SpamFilter comes without pretrained bayesian filter and that why ALL mail are legitime if quarantine does not work. I have to switch on quarantine that bayesian filter start learning. That why need manually learning.

But unfortunately i can't make one thing. Larger part of spam mail comes to non-existent users. I can't direct it to bayesian filter. Now i use WhiteTO list. May be you are prompt me how do this.

Posted By: LogSat
Date Posted: 03 October 2004 at 8:55pm
Alexey,

You don not have to turn on quarantine in order for the Bayesian filter to work. You just need to let the other filters (SpamFilter comes with default settings that will already catch a lot of spam) to their job. As emails arrive and are blocked, the bayesian filter will learn and eventually kick in as well.

Roberto F. LogSat Software

Posted By: Guests
Date Posted: 04 October 2004 at 6:02am
Maybe I don't understand something? For example, I'm installing SpamFilter on new system. Quarantine is off, bayesian corpus have zero size. HOW bayesian filter can distinguish spam from non-spam mail?

Posted By: LogSat
Date Posted: 04 October 2004 at 6:02pm
SpamFilter has several other filters that block spam. For example the MAPS servers, the "No Reverse DNS" server, the keyword filters. All of these will block spam, even if the quarantine is disabled.

Please also note that all the quarantine does is to save a copy of blocked emails in a database so they can be retrieved later.

Roberto F. LogSat Software


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