Each incoming e-mail is scanned for signs that it may be spam, and if it is determined that it's likely to be spam, it is altered to clearly reflect this, so that you -- the user -- can decide whether to delete or keep it.
The spam-identification tactics used by Spam Assassin include:
 Header analysis: spammers use a number of tricks to mask their identities, fool you into thinking they've sent a valid mail, or fool you into thinking you must have subscribed at some stage. SpamAssassin tries to spot these.
Text analysis: again, spam mails often have a characteristic style (to put it politely), and some characteristic disclaimers and CYA text. SpamAssassin can spot these, too.
Blacklists: SpamAssassin supports many useful existing blacklists, such as mail-abuse.org, ordb.org or others.
Razor: Vipul's Razor is a collaborative spam-tracking database, which works by taking a signature of spam messages. Since spam typically operates by sending an identical message to hundreds of people, Razor short-circuits this by allowing the first person to receive a spam to add it to the database -- at which point everyone else will automatically block it.
Once identified, the mail can then be optionally tagged as spam for later filtering using the user's own mail user-agent application.
SpamAssassin requires very little configuration; you do not need to continually update it with details of your mail accounts, mailing list memberships, etc. It accomplishes filtering without this knowledge, as much as possible. Features:
Wide-spectrum: SpamAssassin uses a wide variety of local and network tests to identify spam signatures. This makes it harder for spammers to identify one aspect which they can craft their messages to work around.
Free software: it is distributed under the same terms and conditions as Perl itself.
Easy to extend: Rules, weights and user-visible text are stored in text configuration files as much as possible, which the user (or sysadmin) can edit to modify or add new rules.
Flexible: SpamAssassin encapsulates its logic in a well-designed, abstract API. As a result, it's not limited to the traditional local-delivery-to-spool case; using the Mail::SpamAssassin classes, it can be used in a wide variety of setups. This means that SpamAssassin support is available for a variety of mail systems -- traditional procmail, a Mail::Audit plugin, qmail, MIMEDefang, Postfix, and many others.
 show feedback form
 close
by KeysCapt 
last modified: 2002-12-19 14:57:37 |
