org.apache.james.transport.mailets
Class BayesianAnalysis

java.lang.Object
  org.apache.mailet.GenericMailet
      org.apache.james.transport.mailets.BayesianAnalysis

All Implemented Interfaces:

Mailet, MailetConfig

public class BayesianAnalysis
extends GenericMailet

Spam detection mailet using bayesian analysis techniques.

Sets an email message header indicating the probability that an email message is SPAM.

Based upon the principals described in: A Plan For Spam by Paul Graham. Extended to Paul Grahams' Better Bayesian Filtering.

The analysis capabilities are based on token frequencies (the Corpus) learned through a training process (see BayesianAnalysisFeeder) and stored in a JDBC database. After a training session, the Corpus must be rebuilt from the database in order to acquire the new frequencies. Every 10 minutes a special thread in this mailet will check if any change was made to the database by the feeder, and rebuild the corpus if necessary.

A org.apache.james.spam.probability mail attribute will be created containing the computed spam probability as a Double. The headerName message header string will be created containing such probability in floating point representation.

Sample configuration:

 <mailet match="All" class="BayesianAnalysis">
   <repositoryPath>db://maildb</repositoryPath>
   <!--
     Set this to the header name to add with the spam probability
     (default is "X-MessageIsSpamProbability").
   -->
   <headerName>X-MessageIsSpamProbability</headerName>
   <!--
     Set this to true if you want to ignore messages coming from local senders
     (default is false).
     By local sender we mean a return-path with a local server part (server listed
     in <servernames> in config.xml).
   -->
   <ignoreLocalSender>true</ignoreLocalSender>
   <!--
     Set this to the maximum message size (in bytes) that a message may have
     to be considered spam (default is 100000).
   -->
   <maxSize>100000</maxSize>
 </mailet>
 

The probability of being spam is pre-pended to the subject if it is > 0.1 (10%).

The required tables are automatically created if not already there (see sqlResources.xml). The token field in both the ham and spam tables is case sensitive.

Since:

2.3.0

Version:

CVS $Revision: $ $Date: $

See Also:

BayesianAnalysisFeeder, BayesianAnalyzer, JDBCBayesianAnalyzer

Constructor Summary

BayesianAnalysis()

Method Summary

long	getLastCorpusLoadTime() Getter for property lastCorpusLoadTime.
java.lang.String	getMailetInfo() Return a string describing this mailet.
int	getMaxSize() Getter for property maxSize.
void	init() Mailet initialization routine.
void	service(Mail mail) Scans the mail and determines the spam probability.
void	setMaxSize(int maxSize) Setter for property maxSize.

Methods inherited from class org.apache.mailet.GenericMailet

destroy, getInitParameter, getInitParameter, getInitParameterNames, getMailetConfig, getMailetContext, getMailetName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BayesianAnalysis

public BayesianAnalysis()

Method Detail

getMailetInfo

public java.lang.String getMailetInfo()

Return a string describing this mailet.

Specified by:

getMailetInfo in interface Mailet

Overrides:

getMailetInfo in class GenericMailet

Returns:

a string describing this mailet

getMaxSize

public int getMaxSize()

Getter for property maxSize.

Returns:

Value of property maxSize.

setMaxSize

public void setMaxSize(int maxSize)

Setter for property maxSize.

Parameters:

maxSize - New value of property maxSize.

getLastCorpusLoadTime

public long getLastCorpusLoadTime()

Getter for property lastCorpusLoadTime.

Returns:

Value of property lastCorpusLoadTime.

init

public void init()
          throws javax.mail.MessagingException

Mailet initialization routine.

Overrides:

init in class GenericMailet

Throws:

javax.mail.MessagingException - if a problem arises

service

public void service(Mail mail)
             throws javax.mail.MessagingException

Scans the mail and determines the spam probability.

Specified by:

service in interface Mailet

Specified by:

service in class GenericMailet

Parameters:

mail - The Mail message to be scanned.

Throws:

javax.mail.MessagingException - if a problem arises