Work the E-mail, Part I

Postfix can store strings and filtering expressions in many indexed or linear maps. These structures are used to store information on how to deal with clients, senders and single messages. Indexed maps are binary databases built from regular text files. External relational databases also can be used as indexed maps. Linear maps are regular text files read from top to bottom until a matching record is found, so the order of the record matters.

This article is an introduction to the topic of this series, rather than a practical tutorial in order to clarify some general concepts. But, don't worry; we'll get to the practical concerns in the next article. In the meantime, take a quick look the documentation listed in the Resources and keep it handy for when you read “Work the Mail, Part II”. You also are welcome to write me directly about any specific e-mail tip you would like to find in this series.