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
- 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
- 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
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.