Subject: Re: processing outgoing e-mail
To: Wojciech Puchar <>
From: Izaac <>
List: netbsd-users
Date: 09/17/2002 16:14:27
On Tue, Sep 17, 2002 at 04:50:26PM +0200, Wojciech Puchar wrote:
> is it possible for sendmail to additionally process somewhat (simple
> piping to procmail would be enough) not only incoming but outgoing mail?


                         Filtering Mail with Sendmail


   Sendmail's Content Filter API (milter) provides third-party programs
   to access mail messages as they are being processed by the Mail
   Transfer Agent (MTA), allowing them to examine and modify message
   content and meta-information. Filtering policies implemented by
   Milter-conformant filters may then be centrally configured and
   composed in an end-user's MTA configuration file.

   Possible uses for filters include spam rejection, virus filtering, and
   content control. In general, Milter seeks to address site-wide
   filtering concerns in a scalable way. Individual users' mail filtering
   needs (e.g. sorting messages by subject) are left to client-level
   programs such as Procmail.

   This document is a technical introduction intended for those
   interested in developing Milter filters. It includes:
     * A description of Milter's design goals.
     * An explanation of Milter application architecture, including
       interactions between the support library and user code, and
       between filters and the MTA.
     * A specification of the C application programming interface.
     * An example of a simple Milter filter.



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