This is a python implementation of the GOSSiP protocol. Author: Stuart D. Gathman Copyright 2005,2006,2007 Business Management Systems This code is licensed under the GNU GPL, see COPYING. Pygossip is based on the GOSSiP project: http://gossip-project.sourceforge.net/ The python package provides client and server library modules. The server module stores reputations as Observations objects in a shelve database. The server module is used by the bms.py milter in pymilter, and when a senders spam/ham ratio gets too high, their emails are rejected at MAIL FROM. This is much more efficient than scanning and quarantining the message, and keeps clutter out of the quarantine so that false positives are more likely to be noticed. The RPM installs a pygossip service, which can aggregate reputation scores from multiple peer servers. Support for this is still experimental, although it is running on six production servers. Reputation is computed from the ratio of spam to ham over the past 1000 observations and ranges from -100 to +100. A confidence score reflects the number of observations and the freshness of the data and ranges from 0 to 100. Peer reputation is computed from how often the peer agrees with us, and confidence in the peers opinion is adjusted accordingly.