Installation guide

Chapter 15. Email 221
Many environment variables are not used by most Procmail users, and many of the more important
environment variables are already defined a default value. Most of the time, you will be dealing with
the following variables:
• DEFAULT — Sets the default mailbox where messages that do not match any recipes will be placed.
The default DEFAULT value is the same as $ORGMAIL.
• INCLUDERC — Specifies additional rc files containing more recipes for messages to be checked
against. This allows you to break up your Procmail recipe lists into individual files that fulfill
different roles, such as blocking spam and managing email lists, that can then be turned off or on
by using comment characters in the user’s .procmailrc file.
For example, two lines in a user’s .procmailrc file may look like this:
MAILDIR=$HOME/Msgs
INCLUDERC=$MAILDIR/lists.rc
INCLUDERC=$MAILDIR/spam.rc
If the user would like to turn off the Procmail filtering of their email lists but leave spam control in
place, they could simple comment out the first INCLUDERC line with a # character.
• LOCKSLEEP — Sets the amount of time, in seconds, between attempts by Procmail to use a partic-
ular lockfile. The default is eight seconds.
• LOCKTIMEOUT — Sets the amount of time, in seconds, that must pass after a lockfile was last
modified before Procmail will assume that the lockfile is simply old and can be deleted. The default
is 1024 seconds.
• LOGFILE — The location and file to contain any Procmail informational or error messages.
• MAILDIR — Sets the current working directory for Procmail. If set, all other Procmail paths are
relative to this directory.
• ORGMAIL — Specifies the original mailbox, or another place to put the messages if they cannot be
placed in the default or recipe-required location.
By default, a value of /var/spool/mail/$LOGNAME is used.
• SUSPEND — Sets the amount of time, in seconds, that Procmail will pause if a necessary resource,
such as swap space, is not available.
• SWITCHRC — Allows a user to specify an external file containing additional Procmail recipes,
much like the INCLUDERC option, except that recipe checking is actually stopped on the referring
configuration file and only the recipes on the SWITCHRC-specified file are used.
• VERBOSE — Causes Procmail to log much more information. This option is useful for debugging.
Other important environmental variables are pulled from your shell, such as LOGNAME, which is your
login name, HOME, which is the location of your home directory, and SHELL, which is your default
shell.
A comprehensive explanation of all environments variables, as well as their default values, is available
on the procmailrc man page.
15.5.2. Procmail Recipes
New users often find the construction of recipes the most difficult part of learning to use Procmail. To
some extent, this is understandable, as recipes do their message matching using regular expressions,
which is a particular format used to specify qualifications for a matching string. However, regular
expressions are not very difficult to construct and even less difficult to understand when read. Addi-
tionally, the consistency of the way Procmail recipes are written, regardless of regular expressions,
makes it easy to figure out what is going on.