Greeneville City Schools

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PostPosted: Tue Jul 24, 2007 2:00 pm 
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Joined: Mon May 16, 2005 10:13 am
Posts: 103
Location: Central Office
Greeneville City Schools Email Filter

The Greeneville City Schools filters all email, entering and leaving our system, for content and viruses.

We handle approximately 1 million messages per day. Our normal SPAM percentage is over 99% (over 99% of email directed to our users is SPAM). Presently, we have about a .006% false positive rate.

Our mail filter examines all messages entering or leaving our system. If something in a message triggers a rule, the message is delayed before reaching our mail server. Our mail administrator will manually review these messages. Conditions which will trigger this filter include:

• The most heinous words or combinations of words (use your imagination).
• A message addressed to more than a preset number of our users. We have tried to set the limit high enough to accommodate our largest building.
• A message which contains only remote images. This is a frequent tactic of spammers/pornographers. The message contains a link to an image on their server. Since there is nothing in the message except the link, the message is usually not trapped by mail filters. If someone sends you a web page by email, it will probably be deleted by our filter. You should ask them to send you a link by email.
• We check every email for the name of the server (the part following “@”). If it does not exist, the message is deleted.
• Every email is checked against a list on the Internet of known spammers. If you do not receive email from a particular user or domain, please let us know and we can add them to an approved list.
• The information regarding the sender can prevent a message from reaching you. If a sender’s email client is mis-configured either accidentally or intentionally, we will reject their email. The data we are checking is contained in the header of every message (usually not visible to the recipient). If you are interested in what we are checking, please contact us.
The subject line is blank or very short. You should ensure you ALWAYS use a descriptive subject. "Hi," "Stuff," "Just checking," or other very generic subjects should be avoided. For tips on better email, please read this article.
• The body of the message does not contain much text. One or two word bodies will generally be flagged as spam.
• The message contains several words that cause it to be flagged as spam. Such words may be, but are not limted to, "free," "webcam," "check this out," or any other words that might not be proper, depending upon the context.
• Words which may be proper in the correct context.
• A virus attached to the message. We stop approximately 600 viruses from reaching our users every month.
• The message contains malicious code.
• The message contains an attachment.
• The message contains a video file attachment. To ensure inappropriate content from reaching a classroom, all videos are reviewed before being approved.

When our mail administrator approves a message, the subject of the message will have reason the message attached appended. You should look carefully at why the message was trapped to determine if you need to notify the sender how to word messages in the future which will not be trapped.

If the message contains/is a virus or is malicious, our mail administrator will delete the message and notify you. If you know the sender, you should notify them their computer may be infected with a virus or that they are sending code our mail server deems malicious.

If you continue to receive spam or inappropriate messages, please let John or Larry know.

If you have any questions, please let us know.


Thank you for all you do for the children of Greeneville.

_________________
Larry Jones
Central Office


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