Linux.Desktop.Hacks [Electronic resources] نسخه متنی

Hack 58. Reclaim Your Email with procmail

Manage your email automatically without
depending on your email client.

Email is the Internet's
killer
app. Everybody uses it, everybody loves iteven those who feel
like their lives are controlled by it. The volume of email in our
lives has increased exponentially the last few years, and
I'm not referring just to spam. With
email's acceptance as a mainstream communications
medium, it has become increasingly important for users to manage
their volume of email efficiently. Most GUI email programs provide
numerous features to help manage email, including searching, filters,
and spam-checking. But for some users these features
aren't enough. They have found it best to augment
their email client with the Swiss Army Knife of email processing,
procmail. This email tool allows you to define
what you do with your mail, where it goes (if it goes anywhere), and
how it should be stored using a simple, albeit terse, rule-based
syntax. This hack explores how to use procmail.

To get procmail, use your distribution tools to
search for and install it. For instance, on Debian, use:

foo@bar:~# apt-get install procmail

If your distribution doesn't come with
procmail, you can always download it from
http://www.procmail.org and
compile it yourself.

8.5.1. Configure Your MTA to Use procmail

procmail is typically used
on computers that have a Mail Transfer
Agent (MTA) running, and as such, before you use
procmail you must configure your MTA to use it.
The majority of distributions include a default MTA that, although
sometimes not installed by default, can be installed at a later time.
An example of this is Debian, which includes the Exim MTA as the
default server. You will need to ensure that your MTA is able to send
and receive mail before you can begin configuring
procmail.

Along with the many different MTAs available are many different ways
to configure them to use procmail. Despite the
mass of potential options, an almost foolproof method is to use a
.forward file in your home directory. This file
contains rules that, when followed, invoke
procmail for all incoming mail. The following
command enables procmail for most MTAs:

foo@bar:~$ echo '|exec /usr/bin/procmail' > ~/.forward

If your MTA complains, you might have to use just
|/usr/bin/procmail instead.

8.5.2. Using procmail

procmail rules, better
known
as recipes, are defined in the .procmailrc file
in your home directory. Although a full treatment of the recipe
syntax is beyond the scope of this hack, a simple example shows the
basic format. Add the following to your
.procmailrc file:

:0
*

This simple recipe delivers all mail addressed to you to your default
system mailbox file (usually /var/mail/$USER).
The :0 indicates the beginning of a rule and the
* indicates that all mail should be handled by
this rule. This re-creates what your MTA usually does by default. If
you use the maildir format (the preferred format
of the qmail MTA and the KMail client),
procmail can move all mail to a directory with a
recipe, such as this:

:0
*
Mail/

This delivers your mail into a maildir-formatted
directory ($HOME/Mail by default). If you prefer
standard mailbox format (mbox), you can use
this:

:0
*
mbox

This recipe delivers all your mail to $HOME/mbox
by appending all new mail to the same file. Although these examples
are trivial and do no more than your MTA, they are the most basic
recipes procmail uses. These simple concepts
form the basis behind more complex procmail
recipes.

8.5.3. Standard procmail Usage

Now that you know
how
procmail works, you can use it to do some
processing. Say you want to store mail from your friends Bruce
(}

The {} allow you to combine more than one rule.
The formail utility that is bundled with
procmail allows you to grab various headers and,
in this case, put them in variables for use in the second rule. The
c in :0 c indicates this rule
works on a copy of the incoming message, and the message will
continue on through the various rules that follow.

Other potential uses for procmail include
sending all mail through Spamassassin to root out all the junk and
prevent it from entering your mailboxes.

8.5.4. See Also

procmailex manpage

procmailrc manpage

egrep manpage

Adam Garside