Linux Orbit: Email Filtering: Stopping Viral Attachments with Exim Version 1.0

[ Thanks to John
Gowin for this link. ]

“Email viruses, as a general rule, attack end users with email
clients that allow the execution or opening of attached files. The
easiest way to stop these types of virus attacks is to filter email
with attachments and prevent them from being delivered. This is a
bit like swatting flies with a sledgehammer, especially if it
inhibits productivity within a network. The convenience of email
attachments has been a boon to productivity in the workplace. The
inherent insecurity of email attachments has been the bane of the
network administrator. So how do you find that middle ground to
make both end users and network administrators happy? The first
step is to choose a flexible mail transfer agent like Exim that
allows complex configuration options and email filtering.

“In this HOWTO, we’re going to take a look at using Exim’s mail
filtering properties to aid you in your quest for a virus free
email system. To begin, we’ll take a look at some of the basic
configuration options for Exim located in the main configuration
file /etc/exim.conf. Then we’ll show you how to configure Exim to
filter attachments based on their file type. We’ll also take a look
at the email filter file provided for your use at the Exim Web
site, and show you how to use it as a template for your network
mail filter. We’ll then demonstrate how to install the filter, and
also show you where to look if it doesn’t work properly. Finally,
we’ll look at keeping up with new email viruses and how to add
their file extensions to your filter to keep you mail users
safe…”

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