Procmail - Red Hat LINUX 7.2 Reference Manual

Section 16.5:Procmail 273
• -l <max-number-bytes> — Tells Fetchmail to not download any messages over a particular
size and leave them on the remote email server.
• --quit — Quits the Fetchmail daemon process.
More commands and .fetchmailrc options can be found on the fetchmail man page.

16.5 Procmail

Procmail allows you to filter email as it is received from a remote email server, or placed in your spool
file on a local or remote email server. It is powerful, gentle on system resources, and widely utilized.
Procmail, commonly referred to as a Local Delivery Agent (LDA), plays a small role in delivering
email to be read by an MUA.
In order to use Procmail, it must first be installed. Type the rpm -q procmail command to see
if the procmail package is installed. If, for some reason, Procmail is not on your system, install it
from the Red Hat Linux installation CD-ROMs.
Procmail can be invoked in several different ways. As email is placed on your email spool file, Proc-
mail can be configured to start up, filter the email to locations configured for use with your MUA, and
quit. Or, your MUA could be configured to bring up Procmail any time a message is received so that
messages are moved into their correct mailboxes. In many cases, the presence of a .procmailrc
file in the user's home directory will invoke Procmail, if Sendmail is being used.
The actions Procmail takes with an email are dependent upon instructions from particular recipes, or
rules, that messages are matched against by the program. If a message matches the recipe, then the
email will be placed in a certain file, deleted, or otherwise processed.
When Procmail starts, it reads the email message and separates the body from the header information.
Next, Procmail looks for the /etc/procmailrc file and rc files in the /etc/procmailrcs di-
rectory for default, system-wide, Procmail environmental variables and recipes. Then, Procmail looks
for a .procmailrc file in the user's home directory to find rules specific to that user. Many users
also create additional rc files of their own for Procmail that are referred to by their .procmailrc
file but may be turned on or off quickly if a mail filtering problem develops.
By default, no system-wide rc files exist in the /etc directory, and no user .procmailrc files
exist. To begin using Procmail, you will need to construct a .procmailrc file with particular envi-
ronment variables and recipes explaining what you would like to do with certain messages.
In most configurations, the decision as to whether Procmail starts and attempts to filter your email is
based the existence of a user's .procmailrc file. To disable Procmail, but save your work on the
.procmailrc file, move it to a similar file's name using the mv ~/.procmailrc ~/.proc-
mailrcSAVE command. When you are ready to begin testing Procmail again, change the name of
the file back to .procmailrc. Procmail will begin working again immediately.