In order to help you understand the way Procmail rules work, we will go through the design and setup of several simple but very useful rule sets. This should help to get you into the swing of designing your own rule sets as you find more specific needs to filter your incoming mail items.
All these examples are based on the mail messages received from the Freelancers mailing list from which the previous example headers were taken. They all achieve the same result and once again prove that there is no one correct solution to a programming problem.
This header explains who the originator of the e-mail was. There are a variety of formats that may be used and are formed of various combinations of human-readable and computer-readable items of information. When you have looked at a few e-mails, you will begin to see the various patterns that can be used by differing mail systems and software. The actual formatting of this header is not necessarily important as you are...