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spamass-milt http://savannah.gnu.org/projects/spamass-milt/ is a sendmail milter by Georg C. F. Greve, which allows sendmail users to filter spam at the heart of the sendmail message pipeline. It also allows SpamAssassin to be used for UUCP sites. If you plan to use this, be sure to read Kevin McGrail's walkthrough at Peregrine Hardware. http://www.peregrinehw.com/downloads/SpamAssassin/INSTALL-spamassmilter.
milter-spamd http://www.benzedrine.cxch/milter-spamd.html is a simple BSD-licensed sendmail milter by Daniel Hartmeier.
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