As a tool for advanced users, the Procmail application acts as a filter for email, as it is retrieved from a mail server. It uses rulesets (known as recipes) as it reads each email message. No default configuration is provided; you must manually create a
~/.procmail file for each user, or users can create their own.
There is no system-wide default configuration file. The creation of the rulesets is not trivial and requires an understanding of the use of regular expressions that is beyond the scope of this chapter. Ubuntu does provide three examples of the files in
/usr/share/doc/procmail/examples, as well as a fully commented example in the
/usr/share/doc/procmail directory, which also contains a README and FAQ. You can find details ...