smtp-vilter is a high-performance content filter for sendmail, which detects email viruses and spam. It can pass, discard, or simply mark an email based on the results of a content scan. It relies on third-party products for the actual content scan. It uses the milter API to communicate with sendmail, and backends to communicate with the actual scanning engines. The backends can be chained to perform a series of checks on each message in one run.
