It is a known fact that Email Spam (or Junk Email) cause annoyance and pose security threats to our users. What is not trivial and yet has significant impact to users is that these spam emails use up a lot of system resources and affect the quality of the Email services. Since last fall, the amount of total emails received from outside has sharply increased to a level that our Email services were seriously affected. According to the statistics generated by the spam-detection software, at least 50% of those emails were almost certain to be spam. A lot of system resources were thus wasted on processing those spam emails and the delivery of normal email was often delayed by hours!

It is necessary to curb the problem by adopting the appropriate method to handle email spam without affecting the users too much. Thus, the Committee on Information System and Technology (CIST), at its last meeting in December 2006, unanimously agreed to adopt the "drop method" approach to remedy the situation. Under this approach, those email messages that are tagged by the reliable spam detection software with a "spam level" score equals to 99% or above (that means they are almost certain to be spam) will be automatically dropped at the incoming email gateway.

The adopted approach has been implemented since 8 January 2007. Together with other email system enhancements (Ref: Network Computing Issue 50 - December 2006), the following benefits have been achieved:

• Reduce the delay of email delivery and the chance of email congestion. Especially, the average delay of delivering internal email has reduced from 30 minutes on average to less than ONE minute!
• Reduce complaints from external parties regarding the bouncing of undeliverable spam email messages.
• Save significant system resources from delivering several tens of thousands of junk email messages everyday.
• Save storage space (both system and user mailbox spaces) from storing the junk email messages. Those junk emails, if not dropped, will occupy several hundreds of Mbytes of storage space everyday.

The Computing Services Centre (CSC) will regularly review the situation of spam handling process and the email server performance in order to ensure the quality of the email services.