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Chapter 15. Email

    quit

  Quits the Fetchmail daemon process.

More commands and

.fetchmailrc

options can be found on the

fetchmail

man page.

15.5. 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 used.

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

direc 

tory 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 environment

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 ~/.procmail 

rcSAVE

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.

15.5.1. Procmail Configuration

Procmail configuration files, most notably the user's

.procmailrc

, contain important environmental

variables. These variables tell Procmail which messages to sort, what to do with the messages that do

not match any recipes, and so on.

These environmental variables usually appear at the beginning of

.procmailrc

in the following

format:

env variable ="

value "

In this example, the

env variable

is the name of the variable, and the

value

section defines

the variable.