|
|
HOME >
CHAPTER 9
Chapter
9; Bayesian Filtering
The
Bayesian filter in SpamAssassin is one of the most effective
techniques for filtering spam. Although Bayesian statistical
analysis is a branch of mathematics, one doesn't necessarily need to
understand the mathematics to use SpamAssassin's Bayesian filter.
Bayesian analysis
involves teaching a system that a
particular input gives a particular result. For Spam filtering, this
teaching is repeated, many times over, with many spam and ham
emails. Once this is finished, a Bayesian system can be presented
with a new email and will give a probability of the result being
spam. For best results, teaching should be a constant process.
To filter
spam emails, the system is taught both ham and spam emails, until
the filter has learned to differentiate between the two. Then,
emails passed through the filter will be assigned a probability of
being spam. When Bayesian filtering is used in conjunction with
SpamAssassin's other spam detection rules, SpamAssassin approaches
100% detection of spam, with false positives (legitimate emails
misclassified as spam) close to 0%.
Internally, the Bayesian engine provides a single probability figure
for each email processed. This probability ranges from 0 (0%
likelihood that an email is spam) up to 99 (99% likelihood).
In this chapter, the focus is on users who have an account on the
local machine. A Bayesian database can be implemented using an SQL
database. The principles of the Bayesian database are also valid for
an SQL Bayesian database. Creating an SQL Bayesian database is
covered in Chapter 14.
|
 |
|
 |
| |
Paperback,
220 pages
Released: Sept 2004
ISBN: 1904811124
Author: Alistair McDonald |
|
|
|
|
|
Intro
1. Introducing Spam
2. Spam and Anti-Spam
Techniques
3. Open Relays
4. Protecting Email Addresses
5. Detecting Spam
6. Installing SpamAssassin
7. Configuration Files
8. Using SpamAssassin
9. Bayesian Filtering
10. Look and Feel
11. Network Tests
12. Rules
13. Improving Filtering
14. Performance
15. Housekeeping and Reporting
16. Building an Anti-Spam Gateway
17. Email Clients
18. Choosing other Spam Tools
Appendix A
Index
|
 |
|
View the book details
on PacktPub.com
|
 |
