  The Internet has dramatically changed the relationship among people and their
relationships with others people and made the valuable information available
for the users. Email is the service, which the Internet provides today for its
own users; this service has attracted most of the users' attention due to the
low cost. Along with the numerous benefits of Email, one of the weaknesses of
this service is that the number of received emails is continually being
enhanced, thus the ways are needed to automatically filter these disturbing
letters. Most of these filters utilize a combination of several techniques such
as the Black or white List, using the keywords and so on in order to identify
the spam more accurately In this paper, we introduce a new method to classify
the spam. We are seeking to increase the accuracy of Email classification by
combining the output of several decision trees and the concept of ontology.
