What is SpamAssassin?
SpamAssassin is a very popular program that is used at CSE to help detect spam email. It uses a number of methods, including checking mail headers for invalid or forged information, as well as analysing the content of emails to determine the likelyhood of the mail in question being spam. Each mail is given a score representing how likely it is to be spam, and if the score is above a certain (configurable) threshold, the mail is marked as spam. This 'marking' of email as spam is done by adding lines to the header of the email.For example, an email that was checked for spam and was marked as being spam would have a line in its header similar to this:
X-Spam-Flag: YES
as well as some other information indicating which tests SpamAssassin used to determine that it was a spam email.
For information on how to filter out such emails, see the FAQ entry on Filtering out spam.
More information on SpamAssassin can be found from its homepage.