# TheBat! An antispam filter BayesIt!

## Filtration of an entering spam by means of a plug-in * BayesIt! *

In popular program The Bat! There is a built in opportunity to filter incoming mail by means of special connected modules plug-ins which can be developed by foreign developers. The connected filter at reception of mail estimates each incoming letter on a scale from 0 up to 100.0 means, that the letter "good", 100 - what is it a spam. Then TheBat! Can something make on the basis of this estimation with the letter - for example, to remove a spam or to place it in a special folder "paper for
recycling". The main advantage of such approach consists in absence of necessity to start foreign programs for check of incoming mail, therefore filters work only at started Bath and at reception of mail.

# Antispamers filter BayesIt

## the Filter developed * Alexey Vinogradovym * on algorithm of a filtration of Bayes

the Given method is based on statistical data collected with received letters. Here that the author on the site devoted writes to algorithm of Bayes
- http://klirik.narod.ru/usefuls/bayesyan.htm

The essence of a method of a statistical filtration consists in application of the mathematical theorem of Bayes to incoming letters. This theorem allows to calculate probability of successful fulfilment of some event on the basis of statistics of fulfilment of this event in the past. With reference to a filtration of a spam: if 9 from 10 letters containing a notorious word "cow", are a spam, and only one - the "good" letter the
theorem of Bayes allows to calculate, with what probability the following letter containing this word, will be a spam.

The method of Bayes means use of statistical estimated base - two sets ("cases") of letters, one of which is made of a spam, and another - from "good" letters. At creation of this base the quantity of ocurrences of each separate word (token) in each case is counted up, and on the basis of it for each token the estimation, or "spam" is calculated.

** Download
BayesIt ** 0.8.1 Release and also a Russifier to it (Language module BayesIt! (Russian)) it is possible on page of a product on a site of program The Bat!:

- Download BayesIt on ritlabs.com: http://ritlabs.com/ru/solutions/bayesit/download.php

Adjustment Bayesit is not strongly complex, enough to esteem on-line the documentation located on the same site: http://www.ritlabs.com/ru/solutions/BayesIt.php