How the E-mail Defense System Works 

Launch the E-mail Defense System!

Northwestern's E-mail Defense System (EDS) scans incoming e-mail messages for accounts that reside on one of the central e-mail servers (casbah, hecky, lulu, and merle) for junk e-mail and virus threats.

Identifying junk e-mail

EDS contains several hundred "junk e-mail" tests that analyze individual characteristics of each message. Each test carries a numerical weight. When a message is analyzed by EDS, the weights of all junk e-mail tests that matched the message are added up and converted to a score that expresses the message's "junk e-mail probability." Based on these multiple tests, the message is then assigned a junk e-mail probability rating between 0 and 100. The higher the junk e-mail probability rating, the more likely the message is to be marked as junk.

Quarantined messages

Junk e-mail will be safely quarantined (placed in an isolated location on the network) for the intended recipient to access and review at any time.

Quarantine notification

An e-mail digest that contains a list of newly quarantined e-mails will be sent to each e-mail recipient daily during off-peak hours. E-mail recipients can decide which quarantined messages should be sent to their inbox or deleted entirely. In addition, users will have the ability to manage what gets quarantined to ensure that desired e-mails are delivered appropriately.

Users who do not plan to check quarantine digests daily can turn this feature off/on. To do so, use the Options menu on the EDS site and uncheck (or check) the box reading "E-mail me the EDS Quarantine Digest, a daily notification of junk e-mail blocked by EDS."

Identifying viruses

EDS uses antivirus definitions much like the antivirus software installed on users' personal computers. Messages that are identified as viruses are immediately prevented from delivery to the mail servers, eliminating any potential threat.

How EDS evaluates e-mail

Incoming e-mail	Action taken by EDS
Low junk e-mail probability messages (safe messages)	Delivered to the e-mail recipient's inbox immediately.
High junk e-mail probability messages (junk e-mail)	Deleted or quarantined in a special inbox on the junk e-mail filter server for later review by the recipient.
Faculty/Staff/Graduate Students	Messages with greater than 99 probability rating are automatically deleted. Messages with 50 - 99 probability rating are sent to quarantine.
Undergraduate Students	Messages with 50 - 94 probability rating are blocked and sent to quarantine. Messages with probability higher than 94 are automatically deleted.
Alumni	Messages with 50 or higher probability rating are automatically deleted.
Virus detection (attachment contains a virus)	Deleted and prevented from delivery.

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NUIT Support Center

Central helpdesk for faculty, staff, and students.
847-491-HELP (4357)
consultant@northwestern.edu