Institute of Information Science, Academia Sinica

Computer Center


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Junk Mail Filters


The email filter system of IIS uses the open source Sendmail+mimedefang+SpamAssassin+greylist, accompanying sophos for email virus scan. Sophos is an anti-virus software purchased by Academia Sinica. The virus pattern file is updated every hour. Since 2007 Sophos is replaced by CLAMAV. SpamAssassin is a junk mail filter developed by It gives every mail a weighted score based on the characteristics of mails. If this score exceeds certain threshold, the mail will be treated as junk. Since Feb 2007 GREYLIST is also included for filtering.

Virus Filter

If the system detects virus contained in a mail, a notification will be sent to the designated recipient. The mail will not be sent to the recipient. Currently zip files are not scanned. Please be very carefull on the zipped file, especially if it contains some executables.
The system will discard the attachment of mail if

Spam Filter

The system detects spam based on the following rules. If the mail is not sent in a standard format, it's easy to be detected as spam. Currently we add "** IIS-Spam **" in the subject field for the spam without discarding them. If you use email clients, there's a filter function that you can put all these spam to cirtain mailbox. However with IMAP the function is not supported by OUTLOOK, but is supported by NETSCAPE and MOZILLA.

Other Filter

Emails have any the following property will not be sent by the mail server If other research groups would like to reject all the mails coming from non-IIS address, please contact the computer center.

User-Defined Rules

Users can set up their own rules by logging to