This is the Distributed Checksum Clearinghouse (DCC) package, including
the command line (e.g. procmail) interface, dccproc; the SpamAssassin
and Postfix interface, dccifd; the Sendmail milter interface, dccm;
the DCC server, dccd; and the DCC greylisting server, dccd-grey.

Also included are utilities such as cdcc and all of the manual pages
and documentation.

WWW: https://www.rhyolite.com/dcc/