About SpamAssassin


What it is and how it works

Panix makes SpamAssassin available and supports it for filtering spam as it is delivered to your account.

Rather than using specific addresses, SpamAssassin uses a series of tests to look for "key phrases" and other indicators of spam in an email message. Each of these tests has a point value, and the message gets a score that is the total of the points for all the tests it matches. If the score is above a given threshold, the message is treated as spam. You can adjust the point value for any of the tests, and/or you can change the threshold setting. You can also control what happens to mail that scores in the Spam range: You can trash it without looking at it, put it into a special folder of your own choosing, or put it into your inbox with a special header to distinguish it from the rest of your email.

For full details, please see the SpamAssassin web page at spamassassin.apache.org/.

Because SpamAssassin is third-party software, upgrades may result in changes in the point value of any of the rules. (We make occasional local changes, but they are rare.) We advise users to allowlist addresses they wish to protect.

Panix users can enable Spamassassin either from the webmail interface or via procmail. Please do not use both. (Not only does it waste system resources, it complicates the process of determining what might have happened to a given piece of mail.)

Allowing and blocking addresses

Allowing simply means adding a known good address to a list that will either bypass SpamAssassin entirely or will give messages from that address a very low (i.e. large negative number) score. SpamAssassin's built-in allowlisting function is easy to enable from the webmail interface. If you're using procmail to run SpamAssassin (spamc), you have an alternative, described here.

You might think that SpamAssassin would also be good for blocklisting spammers' addresses, but this is not the case. First, spammers tend to use one-time addresses, or forge legitimate addresses. Blocklisting these accomplishes nothing and might cause mail from legitimate senders to be trashed. Also, the file that contains these addresses becomes bloated. Once the file becomes too large (over 1024 non-blank lines), SpamAssassin stops working entirely. Blocklisting is fine for dealing with small numbers of specific known addresses-- former friends whose email is no longer welcome, say.
Other SpamAssassin Resources:

Last Modified:Tuesday, 22-Feb-2022 08:47:30 EST
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