Procmail provides a number of predefined macros and environment variables that you can use in your
procmailrc file. They are presented here in alphabetical order along with an explanation and examples of their use.
In the list of variables below we show the type of value that can be assigned to each variable. These types can be “boolean” where “true” or “false” are acceptable values,”integer” where any whole number is acceptable, “path” where a valid pathname for your filesystem is an acceptable value, or “string” where just about any string is acceptable (unless extra qualifications are given in the description).
For variables taking a boolean value there are a number of valid ways to specify true or ...