SPAM is an internet slang term for electronic mail which is the equivalent of junk mail. It is used for direct mail advertising. The most common services advertised by this means are: bulk email services (surpirse surprise), shonky investment schemes and pornographic material.
The purveyors of this material go to great lengths to make it difficult to filter this garbage out of the mail stream.
What I have written is a set of filters using procmail and a helper application to attempt to divide your incomming mail into spam and legitimate mail. These filters are heuristic, so there is always some risk that legitimate mail will be sent to the wrong folder.
There are two sorts of filtering employed, some filters look at properties of the headers (for example that the adresses in them realy exist), these are mostly implemented by the helper application. The other filters look at the content of the body of the mail item.
Before these filters are let loose on the mail of users who don't understand how they work, I would like to test them on a set of computer literate users who can cope with any misbehviour by the filters. The feed back I need is for you to pass to me any legitimate mail that goes into the spam folder and any junk mail that makes it past the filter. Comments on the filters themselves are also welcome. The helper app is in /home/stephen/bin/spamheaders it is written in tcl but is heavily commented.