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Our Spam + Virus Filtering product is
a result of several man hours of testing, configuration, research
and development by our in house staff allowing to use your email
without hindrence from junk and virus bourne mail, however formed and
sent to you.
The Filter works on a separate and extremely powerful
mail server cluster to our regular POP3 mail delivery machines; preventing a deluge of
spam from impacting on normal mail delivery. Each email is scanned and checked
against thousands of different rules to determine the likelyhood of it
being junk or geniune mail.
Heuristics Engine
Thousands of tests check the message headers and content for tell tale
signs of spam. The originating mail server and senders address are verified to
prevent spoofing. We proactively monitor and adapt the tests used by
by the filter to any new techniques the spammers employ.
Bayesian Probability Algorithms
Bayesian algorithms are used to build up a database of the
characteristics of unwanted mail and the characteristics of
legitimate mail. The database can then be consulted to determine
the likelihood of any particular message being spam. Furthermore,
through continually analysing messages the database is actively
updated as the nature of spam changes, creating a form of self
evolving intelligence.
Checksum Databases
Any message has a unique checksum, as users report unsolicited mail
messages, their checksums are added to a database. Several
collaborative checksum databases are consulted to ascertain
whether the message concerned matches one previously
identified as spam by another Internet user.
Real Time Blackhole Lists
Several real time blackhole lists (RBLs) are maintained on the Internet
which catalog known sources of spam. The Spam filter checks for the
presence of the originating mail servers in any of these lists.
Vipul's Razor
As well as the standard networking tests, the new version will utilise a
"Razor client" to link in with Vipul's Razor network. This technology has
not been used before now due to the large overhead that is involved in its
use.
The following summary of Vipul's Razor, taken directly from the author,
explains the ins and outs of the protocol:
Vipul's Razor is a distributed, collaborative, spam detection and
filtering network. Through user contribution, Razor establishes a
distributed and constantly updating catalogue of spam in propagation
that is consulted by email clients to filter out known spam. Detection is
done with statistical and randomised signatures that efficiently
spotmutating spam content. User input is validated through reputation
assignments based on consensus on report and revoke assertions which in
turn is used for computing confidence values associated with individual
signatures.
Pyzor
Pyzor is a Python implementation of Razor, which runs much in the same way
but via an alternative network. Consulting both networks greatly improves
the filter's capability to catch otherwise low scoring messages.
OCR
The introduction of Optical Character Recognition scanning techniques is
the latest addition that we are most excited about. With the latest trend
of spam messages bestowing sole image files, previous attempts atfiltering
them have largely been ineffective and has affected many spamfiltering
providers.
With this new method, as well as the body and headers of messages being
scanned for common spam words and phrases, any attached or inline images
are also scanned using OCR functions.
Whilst some images are crafted in such a way that they simply cannot
be recognised by OCR, we have seen that over 75% of messages
containing spam images are detected.
Additional Rules
As well as the above new methods, new filtering rules have been
added alongside the existing rules to tackle common spam themes such as:
* Adult orientated
* Message obfuscation
* Stock/finance related
* Spoofed legitimate emails (including phishing techniques)
* OEM software
* Drug and performance related medicines
Virus Scanner
Virus definitions are checked for and updated automatically ensuring
that you are protected against threats as they emerge. The virus
scanner is capable of detecting all known virus types, including
polymorphic or self-encrypting viruses, it is even capable of
scanning the contents of compressed archives such as zip and rar
files ensuring that no virus bearing email can make it to your inbox.
Detailed Reports
Each message scanned and found to be spam can include a detailed text attachment
explaining why the message was considered as such, including the points awarded
to each rule that was matched and the total points scored on the email. |
