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 apache.org. 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 FilterIf 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
- Virus is detected
- File extension is exe, com, bat, or scr
Spam FilterThe 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.
- The sender is in the blacklist. The blacklist is retrieved from the database on the Internet.
- The mail is forged to be outlook format.
Other FilterEmails have any the following property will not be sent by the mail server
- From is forged to be an IIS address
- To is forged to be an IIS address
- Recipient is all-users or researchers, but the sender is not from IIS
User-Defined RulesUsers can set up their own rules by logging to https://smtp.iis.sinica.edu.tw