Forsyth County Schools Email Disclaimer
Forsyth County Schools has implemented a series of technology systems that “filter” all incoming email to detect SPAM (junk mail) and those that contain viruses, certain key words, html scripts, or have other attributes that could potentially be unacceptable for student viewing or compromise network security. Our system also uses a Bayesian filter that uses algorithms to identify messages that are probable Spam. We have set the system to automatically DELETE any email identified as SPAM. Unfortunately, this means that any legitimate mail that is incorrectly identified as SPAM is automatically deleted and there is no way to track or recover any lost messages.
We have had some emails sent to teachers, administrators and employees of the school system that have been reported as being blocked. We realize the scrutiny we get when email is tagged as SPAM, blocked and subsequently deleted. There are many reasons why an email may be blocked by our system and they have been listed at the bottom of the page.
On average, our mail servers are processing over 300,000 incoming emails a day, 90% of which are SPAM. While we realize that blocked email is an inconvenience, we have chosen to error on the side of caution due to the possibility of inappropriate content slipping through and being seen by a student peering over a teacher’s shoulder.
If you have experienced this issue with email communication, we recommend that you check a few items noted below and try again.
· Virus Filter – Messages identified or suspect for Viruses, Trojans, and e-mail exploits will be deleted.
· DNS Blacklist - There are several servers on the internet that maintain a DNS Blacklist for servers know to distribute Spam or to have open relays which allow Spam. Our Filter uses those lists so if someone has an e-mail account on one of the Blacklisted servers then their mail will be blocked. It is their mail server owner who is responsible for being removed from those lists.
· Keyword Checking – There is a long list of Keywords and Phrases that if found in the subject or body of the message will be identified as Spam. Examples would include phrases such as “don’t miss out”, “find out more”, “100% guaranteed”, “please answer quickly”, “call now”, “adult only”, and a host of obscene phrases. Words included would be Viagra, nympho, erotic, and all those words not fit to print. Yes, we know that not every message with one of those is Spam but these are the most common and if they are removed from the filter will let hundreds or thousands of Spam messages through each day.
· Header Checking – Messages will be blocked if the “From” field is empty, contains more than 4 numbers, or uses part of the recipient’s address/name. They will also be deleted if they have html scripts, contain remotely hosted images in the message body or if the message is mostly a graphic file with very little text. Both of those are methods Spammers use to get past the Keyword checking and often result in the obscene pics being displayed in the message. Messages that have false email headers and faulty return addresses will also be blocked.
· Macro Filter – Any files with Macros will be rejected and deleted, both incoming and outgoing. These are a potential security risk due to what could happen when a Word or Excel file is opened with a destructive Macro. Those are extremely easy for an end-user to create and then send to anyone with destructive results as soon as they open it.
· Bayesian – This is the “Smart” filter that uses algorithms to identify potential Spam. It results in a lot of false positives but the decision was made to delete all Bayesian identified messages instead of tagging them and sending them on through. This means that many thousands of messages are deleted each day and are not logged due to the size, so many legitimate messages are deleted as Spam and we have no way to trace what happened.
· Directory Harvesting – If someone sends a message that has several incorrect addresses in the “To:” field then the entire message will be rejected. This helps prevent Spammers from just sending a huge distribution list of potential names and getting lucky with some.
· Custom Blacklist – Individual mail addresses and entire mail domains can be added to a custom list to be blocked.
· File Attachments – Many types of files are blocked for security reasons and include those such as VBS, EXE, COM, BAT, and ZIP. Files such as XLS, PPT, DOC are NOT blocked unless they contain Macros. File attachments are quarantined so if they don’t have a Macro then they can be forwarded on to the recipient if they are work related and the recipient lets us know when they get an automated notification that it was blocked.
Last Modified on June 19, 2007