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We have learned over the years that the
correct defense for fighting virus outbreaks requires more than one
solution. The client and server must have logic installed to detect
virus patterns, and the same is true for a comprehensive battle with
spam and unsolicited mail. With Outlook 2003, we are provided with much
more sophisticated anti-spam tools that allow the end users to define
their own tolerances and manage the deletion of messages and processing
of false-positives. While this does save the administrator from certain
management of spam messages, the load on Exchange Servers will increase
while the same amount of messages are received, and end-users are still
required to filter and sort junk mail, albeit with better management
tools.
On the Server front, Microsoft has
indeed made headway in providing support for blacklist servers and
override support for internal SMTP addresses. One of the most powerful
features of the server-based filtering is the ability to archive or
delete messages. Should you choose to delete messages that are filtered
due to server-rules, you can stop the messages from entering the
Exchange stores and limit the number of junk messages the users must
sort through. Another awesome feature is the ability to drop sessions
from known spam senders.  With a fairly simple script, I
can find the valid SMTP addresses in your network by using random or
known words within an SMTP session. Your SMTP server will indicate
“recipient OK” when I hit a match and I can add it to my spam list. To
thwart this, we can tell Exchange to drop the connection if a match is
made against the Senders list. As cool as this feature is, it does
require that the sender continue to use the name we identified and will
not work for spoofed domains.
Summary
Microsoft has improved the spam
fighting tools in both Outlook and Exchange Server, but the new features
fall short of a complete solution. From, the server side, there is no
detection of spam networks or any way to globally filter messages based
on content. The 2003 versions of both programs provide the administrator
with a base set of tools to help get spam under control, but contain
only newer revisions of features that were included and seldom used in
earlier versions. Fortunately, Microsoft has extended the new Anti-Virus
API in Exchange 2003 to allow third-party vendors to develop their own
Exchange Server snap-ins to embrace and extend the base-set of
components provided with Exchange Server 2003. Specific features that
can be provided by third-party vendors include management tools for
archived messages, support for forwarding servers, detection of spoofed
domains, a comprehensive list of subject and body text filters, the
ability to dynamically update the filter engine and filters list,
web-management tools with statistics, and much more. |
