Slamming Spam: A Guide for System Administrators

Invoking procmail

There are two different ways procmail can be invoked or called. The most efficient way is for the MTA to invoke it directly. This is more difficult to set up, but it uses fewer system resources. The MTA invocation topic is covered in the section titled “Delivery Agent Invocation” and requires MTA setup. The second way is to call it via .forward (or in qmail’s case, .qmail) files in each user’s home directory. Although easier to set up, the per-user forward method uses additional system resources.

There are two different ways Procmail recipes can be called, either system-wide in /etc/procmailrc or per-user (by default, a file called .procmailrc located in each user’s home directory). The system-wide file is called first, and ...