Once SpamAssassin is installed, the next step is to configure your email system to use it. There are a number of ways to do this, often several for each Mail Transport Agent (MTA). Procmail can be used to invoke SpamAssassin on a site-wide basis, and it can also be used for configuring specific users to use SpamAssassin. An alternative approach that will increase performance is to integrate SpamAssassin more tightly into the MTA. The method used depends on the requirements of the site:
If performance is an issue due to the volume of emails handled by the site, inadequacy of hardware resources, or use of the email server for other tasks, then integrating SpamAssassin into the MTA will provide the best performance.
If email usage is low (the number of emails received per day is in the low thousands, with few email peaks) and there are no performance concerns, Procmail is a flexible and simple option.
If only certain accounts need to be filtered, Procmail is simple...
