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NMIA email now incorporates a system called Spam Assassin (SA). By itself, this system does not delete spam. It does subject each email to a suite of tests, each with an associated score (positive or negative), and reports the algebraic sum as an index of the probability the message is spam. A higher number means the message is more likely to be spam. The score is a computer's guess and can be way off. But the score can serve as a useful filtering criterion (see Recipe below)

This score is recorded on the "X-Spam-Level:" header line. Most headers are hidden by email client programs (Outlook, Eudora, etc), however we can make the score visible, if you request it. It will appear as a number of capital Q characters on the "Subject:" line of each message. More Qs means it is more likely spam.

This will allow you to watch the scores which SA reports on desired emails (ham), and use them in the RECIPE below. Just send an email to help@nmia.com to have this Spam Assassin score appear on the "Subject:" line of your email.

The RECIPE can help you determine the score that surely means spam, and make the filtering completely automatic on our systems. Once you have determined that score, let us know and we can eliminate it before you see it.

Most of our users have decided to set their SA score filter at 4, 5, or 6 Qs, but you must use the RECIPE to determine it. This can be adjusted as experience dictates.

-- help@nmia.com

This is a recipe for using Spam Assassin scores to mitigate spam before download.

For some time now, we have been using a computer program to scan all email passing through our systems. It is called SpamAssassin (SA), and it examines email headers and content for tokens known to be associated with spam. It provides a score, a number, included in a special header line, which is a statistical guess at the probability that the message is spam. The scoring is not perfect, and sometimes gives inappropriate scores, but millions are using it now.

If properly and carefully followed, this recipe will reduce received spam levels dramatically. It takes patience and a little time to work properly.

These steps _must_ be taken in sequence, to best manage spam.

1.) Ask to have the SA scores added to the "Subject:" line, where you can see them (normally the score is not seen by most email handlers, i.e., Outlook, Eudora, Netscape, etc). You will begin to see the score as a series of capital Q characters at the end of the "Subject:" line of any message given a positive score by SA. Negative scores are not shown.

2.) (Very Important) Ignore all spam messages and their scores. For a week or two, watch ONLY the ham scores, i.e., on desired messages. Make note carefully of the highest SA score you see on any identified ham messages you get. The Spam scores are not important, they may be very high or even zero, but we must know the highest score seen on _your_ ham messages.

3.) After a few weeks, let us know that maximum score and we can set a discard filter a little higher than that value. Thus you will preserve all ham and eliminate much of the spam. Note, the scores on spam may be higher or lower than that value, no matter. After this is done;

4.) If it seems appropriate, you can then collect samples of any ham messages which you regularly receive, which have the high scores. (only regularly received ham applies here, e.g., mail lists, relatives, friends) Call us and we'll explain how you can forward the headers of those messages to us so that ...;

5.) We can make a white list filter which will flag such messages to bypass any filtering based on SA scores, ensuring delivery of those desired emails. This, in turn, will allow us to lower the score used in the discard filter, getting rid of more spam. This can be done progressively one Q at a time.

6.) This next step may not be needed. If a few especially offensive and repetitive spam messages become annoying, their header information can be collected and used for a black list filter to force their discard. Unfortunately, variations on words are nearly impossible to predict. Therefore, most black lists do little good since the offense rarely repeats exactly.

Other than fine tuning each of these steps, there are a few heroic measures NMIA can consider if you are still getting much more spam than ham.

It cannot be over emphasized: The scores you see on spam messages are of no consequence. If it's spam it's spam, no matter the score. What matters is the scores you find on messages you want to receive, i.e., on ham. So begin by ignoring spam; and focus on the scores assigned to your ham messages. They are the key, and necessary to tuning the best discard filter. That, in combination with a possible white list does most of the job.

Please let us know if you have any questions or when you are ready to begin the next step in the process. Help Desk at NMIA

If You Want To Do It On Your Computer

If you would prefer not to have SA score filtering performed on our systems, you can find instructions for setting up filtering in your mail program here:

http://www.nmia.com/spamfiltering.html

This page includes instructions for setting up the following email clients:

Eudora 4.x
Eudora 5.x
Outlook Express
Outlook 97
Outlook 98
Outlook 2000
Outlook 2002
Netscape 4.7x
Netscape 6.x
Netscape 7.x

If you have questions, please don't hesitate to contact us: help@nmia.com