Using MTL ยป Computation

E-mail Message Scanning

Overview

In order to reduce possible problems with viruses infecting computers on the MTL network as well as other problems caused by certain types of attachments and e-mail content, all messages going through the MTL mail system are scanned. Messages that are found to contain computer viruses are not delivered and are removed from the system. Other messages that contain possibly dangerous attachments/content are cleaned, with said attachments/content being removed and replaced with an informative message regarding what was removed and why. The message is then delivered to the recipient while the sender also gets a message stating that the attachment/content was removed and why. The MTL mail server does a great number of checks on each message ensuring that potentially dangerous attachments/content are disarmed or removed and will not affect the user's client computer when reading their e-mail. Because of the number and variety of checks being made and because spammers and virus senders are constantly changing their tactics thus necessitating changes on the MTL mail server, the list of specific checks that are being done will not be listed here. If you are having a particular problem with a message you were sent or one that you are trying to send, please send an e-mail to mail-problems@mtl.mit.edu detailing the issues that you are having.

Attachment Blocking

Currently, the MTL mail server will block any attachment that contains a virus or is determined to be possibly dangerous content that should not be allowed into the user's e-mail program. If an attachment is found to contain a computer virus then it's associated e-mail message is removed from the system and is never delivered. If an attachment is found to contain potentially dangerous content then it is removed from the e-mail message but the rest of the message is delivered to the recipient along with a note stating that the attachment was removed and why. The sender also gets a message stating why the attachment was blocked from being delivered. For example, a reason for an attachment being blocked could be that it was an executable program (i.e. ends in .exe) and executables are not allowed. Below is a list of file extensions and file types that are currently blocked. If you are having a particular problem with an attachment getting blocked, either one that you are trying to send or one that you are trying to receive, then please send an e-mail to mail-problems@mtl.mit.edu detailing the issues that you are having.

The following filename types/extensions are blocked:


The following file types (no matter what their extension is) are blocked:


Attachment E-mail Notifications

Currently, the MTL mail server will send an e-mail to both the sender and recipient if an e-mail attachment is found to have potentially dangerous content within it (as noted above, this does not occur when attachments are found to contain computer viruses). The recipient will get the original message with the attachment removed along with a note saying why it was removed. The sender will also get an e-mail message stating why the attachment was not delivered to the original recipient. This e-mail is done as an informational service in case the attachment was indeed legitimate and the sender needs to find another mechanism in order to send the attachment to the recipient. In most cases, these attachments, while not containing viruses, are bogus and there should be no need for the recipient to take any action. If you have any questions or problems regarding one of these e-mail notifications, then please send an e-mail to mail-problems@mtl.mit.edu detailing the issues that you are having.

HTML in E-mail

While HTML messages are allowed by the MTL mail server, some particular HTML tags are not allowed due to their dangerous nature and probability that they may cause harm on the user's client computer. If the MTL mail server finds these tags within the HTML message, it will attempt to disarm them. This allows the HTML message to continue to be sent to the recipient but with the dangerous tags being neutralized so that they don't cause problems on the user's client computer. If you have any questions or problems regarding HTML encoded e-mail that you are receiving, then please send an e-mail to mail-problems@mtl.mit.edu detailing the issues that you are having.

Phishing Scams

A common attack by spammers and hackers is to send fraudulent e-mails that appear to be from legitimate companies. They do this in order to try and get you to click on URL links embedded in the mail so you can either give them personal information such as a credit card number or they can try and install malware on your computer without you knowing it. In order to lessen the risk of such phishing e-mails, MTL will alert users to possible phishing scams/attacks within e-mails. While the URL link will not be disabled, you will see a notice stating that this could be a possible phishing fraud/scam. If you have any questions or problems regarding phishing scam e-mails that you are receiving or legitimate e-mails being tagged, then please send an e-mail to mail-problems@mtl.mit.edu detailing the issues that you are having.

Computation

MTL Annual Research Report 2017: View Online