The primary piece of software we use is Spamassassin. This software several method of detecting spam. This software uses the following techniques to detect spam.

• Header analysis: spammers use a number of tricks to mask their identities, fool you into thinking they've sent a valid mail, or fool you into thinking you must have subscribed at some stage. Spamassassin tries to spot these.
  
• Text analysis: again, spam mails often have a characteristic style (to put it politely), and some characteristic disclaimers and CYA text. Spamassassin can spot these, too.
  
• Blacklists: Spamassassin supports many useful existing blacklists, such as mail-abuse.org, ordb.org, SURBL", and others.
  
• Learning classifier: Spamassassin uses a Bayesian-like form of probability-analysis classification, so that a user can train it to recognize mails similar to a training set.
  
• Distributed hash databases: Vipul's Razor, Pyzor and DCC are collaborative spam-tracking databases, which work by taking a signature of spam messages. Since spam typically operates by sending an identical message to hundreds of people, these databases short-circuit this by allowing the first person to receive a spam to add it to the database -- at which point everyone else will automatically block it.
  

Tied with Spamassassin, we use MIMEDefang. MIMEDefang is a framework for filtering e-mail. The primary function the Vistech Spamguard © uses it for is to detect bad e-mail attachments (for example .exe, .bat, .vbs files). It is also used to glue the Worm/Virus software with Spamassassin.

Vistech Spamguard © uses ClamAV to detect worms and viruses. ClamAV is automatically kept up to date by checking with the primary database daily (in some cases, several times a day).

Vistech Spamguard © can also be used with several commercial products. For more information, please contact us.