| By Mark Joseph Edwards |
Quirks in the mailer programs spammers use to deliver mail can be turned against the senders.
This week, I share with you a little-known technique you can use to block a lot of spam before it ever reaches your mail server.
Simple DNS changes eliminate unwanted junk mail
Spam is — of course — a bane on the Internet. It drags down mail-server performance, puts a large load on mail clients, bothers recipients to no end, and causes us to spend money on antispam tools when that money might be better spent elsewhere.
But all is not lost: A little-known technique helps reduce spam levels on mail servers without costing you anything other than a few minutes of your time. (See Ian “Gizmo” Richards’s Best Software column today for tips on blocking spam from client PCs.)
Spammers typically use a number of tactics to deliver junk mail. Some spammers rely on third-party mail servers that relay mail from any sender (typically called an open relay). Others use computers that have been assimilated into botnets, custom mailer software designed to behave similarly to a regular mail server, or any number of other tactics.
In my battles with the spam that is sent to the domains I manage, I have found that many spammers use custom mailer software. As it turns out, a lot of those custom programs have quirks that we can take advantage of to fight back against the spammers.