Redhat System Admin   «Prev  Next»
Lesson 7Combating SPAM
ObjectiveList methods that can combat email SPAM

Combating SPAM

The battle against SPAM is waged on two fronts: legal and technical. Legally, SPAM is not a violation in most governmental regions. In the United States, California leads the fight against SPAM, deeming SPAM a civil offense and fining spammers up to $50 per SPAM email.
Technically, you can configure Linux to block or otherwise filter SPAM. For example, many SPAM emails forge the delivery information, which MTAs and MDAs recognize and block. MTAs and MDAs can check information such as the sender's address, recipient's address, subject, or content for known spammers, known spammer keywords, or any other criteria.

Blacklists

A free framework called the Mail Abuse Prevention System (MAPS) Realtime Blackhole List (RBL) allows SPAM recipients to blacklist spammers. People who receive SPAM submit a copy of the email to administrators at MAPS RBL. The administrators decide if the mail is legitimate SPAM, and if so, put the spammer on the MAPS RBLblacklist[1] .
SPAM recipients can also complain to their own system administrators. The administrators will analyze the email, and if legitimate SPAM, add the spammer to local blacklists.
These blacklists hold the IP addresses of known spammers. An MTA can check an incoming email's source IP address against either the local or the MAPS RBL blacklists and reject mail from a spammer who is on the list.

Discussion

What's your experience with SPAM? Is it a major annoyance in your life, or a minor inconvenience that you tolerate in order to enjoy the greater advantages of email? Are you or anyone you know a spammer?
The next lesson concludes this module

[1]Blacklist: A list of known email abusers, such as spammers.