Implementing Filtering Policies

Milter enables a system administrator to combine third-party filters with Sendmail to implement a desired mail filtering policy. For example, if a system administrator wants to perform the following tasks:

The system administrator can configure the Mail Transport Agent (MTA) to filter messages first through a server-based anti-virus engine, then through a large scale antispam service, and finally append the desired footer if the message still meets the requisite criteria. System administrators can add or change any filter independently.

You cannot control the overall mail filtering environment but system administrators can control the mail filtering environment. Particularly, the system administrator must decide which filters are run, in what order they are run, and how they communicate with Sendmail. You can select these parameters, as well as the actions to be taken when a filter becomes unavailable during Sendmail configuration.