libmilter: libmilter (sendmail Mail Filter API) libmilter: libmilter: The sendmail Mail Filter API (Milter) is designed to allow third libmilter: party programs access to mail messages as they are being processed libmilter: in order to filter meta-information and content. libmilter: libmilter: libmilter: libmilter: libmilter: libmilter: