Installation guide

Chapter 15. Email 225
:0:
* ^(From|CC|To).*tux-lug
tuxlug
Any messages sent from the [e-mail] mailing list will be placed in the tuxlug mail-
box automatically for your MUA. Note that the condition in this example will match the message if it
has the mailing list’s email address on the From, CC, or To lines.
Procmail can also be used to block spam, although this is not a good long-term solution for junk mail.
The following example illustrates a temporary spam filtering solution, where multiple recipes are set
to use a common mailbox to store the junk.
SPAM=junk
:0:
* To??^$
$SPAM
:0:
* ^(To|CC):.*,.*,.*,.*,.*,.*,.*,.*,.*,.*,.*,
$SPAM
:0:
* ^Message-Id:.*
[^@]*
$SPAM
In this example, the junk mailbox is associated with the SPAM variable, so that you can change the
mailbox that holds your spam in one place. Then, three recipes look for messages to send to the junk
mailbox.
The first recipe looks for messages that have no recipient in the To line. The second recipe matches
any messages with 12 or more recipients. The third recipe looks for messages with a bad message ID.
These simple examples are provided to help get you started creating recipes. Consult the many Proc-
mail online resources available from Section 15.7 to see more detailed and powerful recipes.
15.6. Security
Like any other service that flows over a network unencrypted, important email information, such as
usernames, passwords, and entire messages, may be intercepted and viewed, all without the knowl-
edge of the email server or client. When using standard POP and IMAP protocols, all authentication
information is sent "in the clear," meaning that someone on a network between the client and the
remote server can easily view it.
15.6.1. Secure Email Clients
Thankfully, most Linux MUAs designed to check email on remote servers support SSL to encrypt
messages as they are sent back and forth over the network. In order to use SSL when retrieving email,
it must be enabled on the email client and server.
SSL is easy to enable on the client-side, often done with the click of a button in the MUA’s configura-
tion area. Secure IMAP and POP have known port numbers (993 and 995, respectively) that the MUA
will use to authenticate and download messages.
Popular MUAs included with Red Hat Linux, such as Mozilla Mail, mutt, and pine, offer SSL-
encrypted email sessions.