Vipul's Razor is a distributed, collaborative, spam detection and filtering
network. Razor establishes a distributed and constantly updating catalogue
of spam in propagation. This catalogue is used by clients to filter out
known spam. On receiving a spam, a Razor Reporting Agent (run by an end-user
or a troll box) calculates and submits a 20-character unique identification
of the spam (a SHA Digest) to its closest Razor Catalogue Server. The
Catalogue Server echos this signature to other trusted servers after storing
it in its database. Prior to manual processing or transport-level reception,
Razor Filtering Agents (end-users and MTAs) check their incoming mail against
a Catalogue Server and filter out or deny transport in case of a signature
match. Catalogued spam, once identified and reported by a Reporting Agent,
can be blocked out by the rest of the Filtering Agents on the network.