Does Your Host Fight Spam?
By E. E. Lester
Virtually anyone with an email address knows what Spam
is, and has, perhaps, considered giving up the speed, convenience, and
simplicity of email because of it. Those who have their own websites are
more vulnerable than the average person with a single work or home email
address from their company or Internet Service Provider. Email addresses
visible on a website can quickly become Spam magnets, as automated programs,
similar in form to search engine spiders, roam the web, looking for addresses
to which new broadsides of Spam may be fired. Website hosting companies
generally provide their clients email accounts for use with their domain,
but are you with a host that provides those email accounts with Spam and
virus protection?
Local Blacklist Filters
Webmasters shouldn't need to seek out local filters for
their site's contact email addresses. There are a variety of server level
solutions a hosting company can offer to protect their users from unwanted
emails. A most basic step is provision of a very rudimentary "blacklist"
functionality to their users, allowing them to prevent future Spam emails
from arriving from the same address. This type of filter is virtually
worthless in today's Spam environment, though, as it is quite rare to
see unsophisticated email arriving from the same address multiple times.
Spammers have grown far more sophisticated than that. Blacklisting functionality
is only really useful in avoiding email from other real people you don't
particularly wish to hear from anymore.
Keywords and Regular Expressions
More advanced server level Spam filters are available.
A small advance is accomplished using keyword filters. Keyword filters
merely check for instances of a certain string of characters and deny
the message if that string if found. The core problem with keyword-only
filters is they can "over filter". Someone who puts "sex"
on their keyword filter will find receiving local news and event announcements
difficult if they live in a town named "Essex". Some filters
attempt to address this deficiency by using "regular expressions"
in order to build a sophisticated rule set to prevent Spam from reaching
your inbox. Briefly, regular expressions are syntax rules used to identify
certain strings of text or numbers. These rules can be set up to identify
text patterns that are commonly used in Spam. They can become quite complex,
but, as with most any filtering method, are not 100% bullet proof. Some
filters that use regular expressions come with a basic set that can be
appended by the user. Obviously this kind of feature is of little use
to someone not familiar with regular expressions.
Bayesian Filters
Currently the most sophisticated filtering methods use
Bayesian inferences. Bayesian filters take a large data set and determine
the probability a message is Spam based on its similarity to previous
Spam messages. The more emails that are processed and flagged theoretically
make the filter more accurate. Services that provide filtering on an ISP
or host level, like Postini's "SpamAway", filter billions of
emails and provide the highest level of success and fewest "false
positives". SpamAway is already highly intelligent about identifying
Spam and doesn't require any "learning" commands or examples
be provided. The online, browser based interface keeps flagged messages
in an easily accessible "quarantine" and allows the user to
check for any false positives. White list functionality is provided to
aide in the prevention of future false positives. A hosting company offering
such an advanced service takes Spam and virus filtering for their customers
seriously.
About the Author
Mr. Lester served for 4 years as webmaster for ApolloHosting.com
and previously worked in the IT industry an additional 5 years. Apollo
Hosting provides website
hosting, ecommerce hosting, vps hosting, and web design services to
a wide range of customers. Click for more hosting
articles.
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