Mail Alias Service
What is spam?
A good definition of spam exists on the mail-abuse.org web site. In general, we think of spam as unsolicited, mass-mailed e-mail messages. This might include, for example, marketing mail for computer software, a political newsletter, or mail regarding money in a Nigerian bank, none of which you actually signed up for.
Is spam the same thing as a virus?
Not necessarily. Viruses are often sent through "spam" methods -- mass-mailings to lots of people. However, not all spam contains viruses. Some contain scams (such as the Nigerian money mail), advertisements (for pornography, software, furniture -- you name it!) or political propoganda. Some is sent simply to be annoying and may have no meaningful content at all.
What is spam tagging?
Electronic mail comes with "headers." Many mail programs, by default, only show you headers such as "To:", "From:", and "Subject." But there are many other headers there, including postmarks as the mail travels through various machines, and indications about whether or not a piece of mail has been scanned for viruses and spam content.
"Tagging" spam means that some (usually-invisible) headers are set up to indicate whether or not a message is likely to be spam. You can then configure your mail program so that, when mail comes in, it is sorted according to whether or not it's likely to be spam. Your mail program does this sorting by looking at these headers (it can see them even when you cannot), and putting possible-spam mail into a separate mail folder.
What's a folder?
The filters we describe on the spam tagging page create a separate "mail folder" for your possible-spam mail. If you haven't used mail folders before to sort your mail into separate electronic 'piles' (either by hand or automatically), you may find this a useful tool for purposes other than spam. For example, you may want to automatically sort mail from your cousin Tom into a special folder called "Tommy". Or, you might move all the mail about a particular project into a special folder for it as you read it, so that you can quickly find it again later. The filters we describe automatically sort possible-spam mail into a folder called "Spam".
Why can't you just throw it away for me?
Unfortunately, everyone's criteria for spam differs. Also, it's impossible for the mail program to know whether or not you signed up to receive some commercial mail, or whether it's unsolicited and annoying. For example, one person might sign up to receive updates on the price of particular software. Another person might receive similar updates from a spammer, and be quite annoyed by them. The difference isn't usually visible in the message itself. We cannot take a chance of deleting someone's wanted or needed e-mail.
What criteria do you use for spam marking?
We use a fairly standard configuration of the SpamAssassin software. Their web site contains a long and fairly technical list of the tests they use to develop a "spam score" for each piece of mail. This highly complicated algorithm is constantly being adjusted as changes and trends occur in the marketplace and Web.
Can I adjust those criteria?
No, because the central SpamAssassin installation can have only one configuration. However, you can decide what threshold to use to filter spam, by using the advanced instructions for your particular mail program for information on how to do this. The index of instructions is on the spam tagging page.
What if non-spam gets marked as spam?
This is almost certain to happen. This is why we recommend that you filter your "possible spam" mail into a separate mail folder, and look at it before you delete it.
If you regularly receive mail that is being marked as spam but shouldn't be marked that way, you can put an exception rule into your mail filters. Look at the advanced instructions for your particular mail program for information on how to do this. The index of instructions is on the spam tagging page.
What do I do with the marked messages?
We recommend that you look at the messages in your "Spam" folder regularly. Usually you can quickly read through the senders and subject lines and discover if any of the mail is from real correspondents, or is a newsletter or advertisement that you did request. You can then delete the other messages, and move the interesting ones into another folder (possibly your main Inbox).
Isn't this an invasion of privacy?
No human other than you is reading your mail. An automated program is simply adding a header, which does not interfere with the mail or its contents. You can decide to filter your mail or not to filter it -- that decision is up to you.
Updated 9 June 2003. Feedback to KB5MU.