Department of Computer and Information Science

 

Department Email

Any Computer Science major or graduate student at the University of Mississippi can get an account on the department's email server.

The department's email server is named john.cs.olemiss.edu. Addresses are of the form username@cs.olemiss.edu. Users can check their mail by logging in with SSH and using pine or mutt. They can also use POP3 or IMAP via an external email client such as Thunderbird or Outlook. Webmail will be available shortly.

The server acts as the SMTP server for the CS network. Users outside the CS network should use their ISP's SMTP server. John is also the department's personal web server.

Anti-Spam

The server uses SpamAssassin to mark messages as either spam or non-spam. No emails are actually blocked, users must use filters to either delete spam or move it to a separate folder.

All messages will be marked with X-Spam-Score and X-Spam-Flag headers. The X-Spam-Score header looks like this:
X-Spam-Score: 7.04 (*******) DNS_FROM_AHBL_RHSBL,MISSING_SUBJECT
The number represents how "spammy" the email is. As a general rule, anything 4.5 or higher is probably spam and anything above 10 is definitely spam. However, users can decide on their own threshold based on their experience. The asterisks represent the integer portion of the number. This allows email client with limited filtering capabilities to make use of the tag. The text that follows the asterisks is a list of SpamAssassin rules that the email matched. These are of little use to the user, but can help the network administrators debug false positives and negatives.

Some email clients can only filter on fixed strings. The X-Spam-Flag header is set to YES when the email has a score greater than or equal to five. It is set to NO when the score is less than five.

Using a threshold of 4.5, the accuracy of the spam filter is very good. Tests done by the SpamAssassin team show that, on average, for every 10,000 non-spam messages, 3 of them will be labeled as spam, and for every 1,000 spam messages, less than 25 of them will be labeled as non-spam.

Users that experience false negatives (spam marked as non-spam) or false positives (non-spam marked as spam) should bounce (not forward) them to spamtrap@tim.cs.olemiss.edu. They can be used to improve the accuracy of the spam filter. For instructions on bouncing email from your email client, please see this page on the SpamAssassin web site.

Users that need assistance setting up their spam filters on their email client should contact a department network administrator.

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