Are you tired of junk mail yet? I am. At one point, I thought that if I received one more unsolicited email asking me to help a "poor widow in Nigeria" move $10 million into the United States or Canada I'd scream. What a scam!

Recently, I found an easy and free way to filter email--a method that just about anyone can deploy on Windows and Novell systems. If you use the Mercury Mail Transport System, you can quickly establish custom filtering rules that can eliminate just about any kind of unwanted email.

Mercury is a full SMTP mail server with a lot of extras, such as an IMAP server, a Finger server, and a password-changing server. Two interesting Mercury components include its built-in POP3 client and its Content Control subsystem. The POP3 client lets the mail server pick up email from any POP3 accounts you specify, and the Content Control subsystem can filter email that the POP3 client receives or that comes through the SMTP server, if you use Mercury as a full-blown mail server. In effect, you can use Mercury as a junk-mail filtering system with just a few minor changes to the way you receive email.

Configuring Mercury as an email-filtering system is simple: Install the Mercury server, configure the basic settings (e.g., host name, DNS servers, user mail accounts), configure the POP3 client to pick up your POP-based email, configure the content-filtering rules to eliminate unwanted email, and configure your regular POP3 mail client to pick up email from Mercury instead of your usual POP3 mail server.

The Content Control filtering rules are flexible and easy to create, and Mercury ships with a predefined rule set that helps eliminate several common types of junk mail you're likely to receive. You can filter based on several email elements (e.g., header, subject). Writing custom rules involves deciding which aspects of an email message to base a filter on, specifying what content will trigger the rule, and giving the filter a weighted numeric value. The weighted value helps govern what happens to a message when it triggers a rule. For example, here's a rule that captures all email that contains the words "Make Money Fast":

If body contains "make money fast" then weight 50

If you configure the Content Control subsystem to delete all messages with a weight of 50 or above, no email containing the above keywords will ever reach your desktop email client.

The rules are powerful. You can filter based on subject, sender, recipients, body content, and email headers. The rules use typical expressions such as "if," "and," "andnot," "or," and "ornot" and special markup codes for character pattern matching. In addition, the Content Control system lets you insert custom email headers into filtered messages you can then use to refilter the message headers in your desktop email client for special action upon receipt, such as sorting email messages into specific folders.

Mercury supports multiple rule sets and separate blacklist and whitelist files. It also works with the Mail Abuse Prevention System (MAPS), which further helps prevent the spread and receipt of unsolicited email. In addition, Mercury includes other built-in filtering systems that let you automatically perform such actions as forwarding, replying to, copying, extracting, and appending email messages to files--all based on individual email characteristics.

I find Mercury a powerful and inexpensive way to manage email traffic. It's a great full-blown standalone mail server and a terrific POP3 mail relay to help you filter out unwanted email simply. And because it uses a small amount of memory, it won't significantly burden resources. What amazes me most about Mercury is that its developer, David Harris, provides this package free for personal and commercial use. You can easily download a copy of Mercury.