Spamassassin Ndr

SpamAssassin puts its results into an X-line within the message header.
Spam filtering services offered by many retail isps, commercial online spam-filtering services (such as spamcop), mda-based procmail scripts, or packages like spamassassin, are all examples of on-network filtering.
Spamassassin is a highly versatile and configurable spam filtering program that identifies spam by testing for certain predefined "fingerprints" and assigning arbitrary numerical scores where it finds them; messages that exceed a user-adjustable threshold score are then tagged as spam.
While it is arithmetical in nature, spamassassin is not itself a bayesian filter, although bayesian filters can be included as spamassassin tests.
Spamassassin: An open-source spam filtering system currently maintained by the apache software foundation, and used by many small-to-medium-size isps, online businesses, and end-users.
orgAdministrators can specify the tests to be used by their local spamassassin installations, can vary these tests for each user, and can even write their own tests using a basic syntax plus regular expressions.
Spamassassin is typically run on a mail delivery agent so that spam can be held and not downloaded to the user.

spamassassin ndr