Controlling Spam on the Mail Server with Spam Assassin

As spam continues to increase in volume and offensiveness, ITS has been seeking an easy, effective and voluntary method to allow users to delete spam from the mail server before it appears in their mailboxes. ITS is pleased to offer a spam filtering service that we believe offers excellent spam protection in combination with the user's ability to choose the level of protection desired.

We currently use Spam Assassin to review each message as it arrives and assign a level of probability as to whether it is spam or not. The higher the spam rating assigned to a message, the higher the certainty that it is spam. You can see the rating Spam Assassin has assigned by opening a message with in the subject line and looking at the spam score, for example: "SpamAssassin (score=7.856)". The spam score is also indicated in the number of s's in the Spam Score line. For example, "X-GC-MailScanner-SpamScore: ssssssss" means that the message has a level 8 rating because it contains eight s's. In our experience, any message with a spam rating of 10 or above has an extremely high certainty of being spam. Anything below a 3 spam rating has a possibility of being a valid message. Messages between 3 to 10 can be either spam or legitimate email, with the likelihood of the message being spam increasing with each number.

We have added a spam control section within GConline, which allows you to control the level at which you want spam to be deleted (between 4 and 10). By default your spam filter is set for you at level 7, which is usually an adequate level for catching most spam. If more spam is getting through than desired you can decide what level to change to by surveying the spam scores of the spam you're receiving. If you are receiving messages marked as possible spam that are actually legitimate email at, say, level 5, you will want to select a higher filtering level than that. Once you make a selection, you will not be able to view these messages either before or after they are deleted (due to software limitations). It is thus remotely possible that a legitimate email message could be deleted without you knowing it. However, that is highly unlikely if you select spam control level 7 or above. We recommend that you start at a high score and adjust downward based on the rating of the spam you're still receiving.

One of the advantages of the Spam Assassin method is that spam is deleted before you view it from any location.