Virus Filtering for Outgoing E-mails Processed by the MAIL.HKU.HK Server

Since September 2001, the Computer Centre has implemented the e-mail virus filtering system on the three central e-mail servers (HKUCC, HKUSUA, GRADUATE).  The anti-virus system would filter out any virus infected files found from the incoming e-mail messages.  Many users have expressed their appreciation of the usefulness of this virus filtering function that have eased their life in protecting their PCs against computer viruses.

However, we are still receiving from time to time complaint reports that some e-mail messages sent out by our users are spreading computer viruses to others. This kind of problem is most probably caused by those PCs that have been infected by computer viruses and consequently spreading virus infected emails without the notice of the PC owners.

In order to enhance our e-mail virus filtering service so that spreading of computer virus on our Campus Network could further be reduced, we have recently set up the anti-virus program Sophos AntiVirus at the point of our central outgoing e-mail gateway, the SMTP server mail.hku.hk, so that the outgoing e-mails sent through the "mail.hku.hk" gateway will be detected for any known computer viruses. Users using PC-based e-mail client programs, such as Eudora, Netscape and Outlook, are advised to set the "SMTP gateway/outgoing mail server" for their email programs to "mail.hku.hk" to gain the advantage provided by the virus filtering function just discussed..

The features implemented are summarised below:

• E-mail messages going through the "mail.hku.hk" server are detected for any known computer viruses.
• Any virus-infected e-mail messages that are detected will not be forwarded for sending to the recipient(s).
• A notification message will be sent to the owner of the computer or PC that has been involved in sending the virus-infected emails.

• There could be certain rare cases that a legitimate document may be labelled as containing virus (i.e. false-positive) when the document contains some bit-strings that match the known virus patterns or the system cannot recognise the format of the document.  If  you should have encountered such a case by receiving a notification telling that  virus has been found from your email attachment while you know that it should not be the case, please report the case immediately by email ithelp@hku.hk for assistance.

KC Chang
Tel: 2859 7972
E-mail: kcchang@cc.hku.hk