The term Anti-Spam Filtering now encompasses numerous techniques to analyse an email and take a decision whether or not to deliver, quarantine or reject the message.
Basic spam filtering can be achieved by having a blacklist of known spammers or carrying out lookups to DNS Block Lists which offer a degree of protection; however spammers are constantly setting up new mail servers or relaying mail of otherwise good senders not to mention malware which can infect a machine and using its own mail transport agent distribute mail.
To combat today’s spam and keep ahead of the spammers it’s essential to have a filter which not only analyses the reputation of the sender but also analyses the message for anomalies and content using a mechanism such as token analysis.
The Reputation of a sending domain/ip still plays a large part in combating spam as this enables the solution to reject outright around 95% of mail at the connection enabling the solution to perform ever more complex analysis on the remaining 5%.
Solutions normally keep their own onboard recent history of connections used to detect spam waves, DNS and directory harvest attacks and feedback information to central reputation services.
Finally the message structure will be analysed to check that the sender is reachable via reverse DNS then the message is checked to ensure the message is not malformed and that the header information is complete.
Once passed these initial connection checks the message is further processed by performing…
- Email Anti-Malware Protection
- Email Content Control
- Email Encryption
- Email Archiving
- Email Continuity
- Email Classification Solutions
· Email Content Control