Now that we have got the basics of Procmail under our belt, we can move on and start putting together a more complete mail-handling system. The advanced techniques in this chapter are required only if you need a very specialized handling for your mail and are not needed for setting up a basic e-mail server. You may wish to skip this chapter and return to it once your server is fully configured and operational.
We will be using a number of more advanced Procmail capabilities in this chapter. This chapter will cover:
The differences between delivering and non-delivering recipes
The usage of variables, substitutions, and pseudo-variables in advanced recipes
Locking and the use of various flags to control execution
How conditions can be applied to test various parts of a message
Advanced actions to forward, save, or pass a message on to an external program for processing
An introduction to regular expressions
Using Procmail macros to simplify e-mail header analysis
Detailed...