Mindless Ramblings

Tired of spam?

There are several ways to reduce the amount of spam you and others receive. Methods involve using spam filters, blacklists, honeypots, closing relays, and web forms.

First off, spam filters are a great start at reducing the amount of spam you recieve. SpamAssassin and Spambayes are both excellent filters that employ Bayesian filtering. These programs rate the likelyhood of a message being spam and then can perform actions based upon differing percentages. Also, they are "learning" programs that can be trained on what constitutes spam and ham. These two programs work with many e-mail clients; for more information, please check their respective sites.

Blacklists will block messages from known spammers, spamming domains, and, in some cases, even whole countries that the end-user does not anticipate receiving mail from. For instance, I do not know anyone in Bulgaria (no offense to Bulgaria, just needed to pick a country for an example) and could safely block all mail coming from this country.

You may help add to the accuracy of blacklists by reporting spam to services such as SpamCop. Setting up an account is simple and free; although, you will receive faster response times from their web form if you are a paid subscriber. With SpamCop, you may make reports anonymously so that the spammer will be unable to tell who reported them.

A honeypot is a trap designed to entice spammers to collect invalid addresses and waste their time and bandwidth. Some honeypots are setup to monitor who is sending this spam and add the address or domain to a blacklist. Other honeypots generate lists of addresses at the sender's domain so that the spammer spams their own organization. For an easy to setup honeypot, check out Project Honeypot.

An open mail relay is a mail server that allows anyone to send mail through it regardless of whether the sender or recipient has an account on the server. Spammers frequently use open relays in order to avoid having to pay for high bandwidth and also to help obfuscate where a message really came from. If you are running a mail server, please make sure that it is not relaying mail for the entire world.

Finally, many spammers use programs call harvesters, bots, or crawlers to obtain e-mail addresses from web sites. The easiest way to avoid this is to not publish e-mail addresses on websites, and instead have a form for entering this mail. The form would then send the information to a back-end that would actually send the mail. No one reading the site would have any idea what the address of the recipient is. I have written a cross-platform (UNIX-like OSes and Windows), free open-source, program to do this called mailer. If you use this, please let me know; I am trying to track how widely it is being used and this will help me decide how often to update it. Also, if you have any problems with it, please let me know.

If you do not want to or cannot run a binary / executable file on your mail server, let me know. I have written a PHP script that has most of the functionality of mailer and can post it.

posted by carsonb @ 9:42:00 PM