By Jill Reese

In October 2006, spam levels worldwide reached new record highs due to adoption of new techniques by spammers. These new levels did not subside, but have become the new normal spam levels. Spam is now estimated to make up approximately 85 percent of all e-mail traffic. The University of Maryland’s e-mail infrastructure is under increasing stress from these new levels.

On March 3, 2007, OIT implemented new e-mail forwarding hosts in the Mail@umd environment to provide some relief from the spam that plagues us all. These hosts are not only faster, but are running the Mirapoint MailHurdle software for increased spam protection.

MailHurdle records sender and receiver information about each specific mail delivery attempt, which it uses to define a mail “relationship.” If our MailHurdle servers receive a message with unrecorded sender and receiver information, they will delay the message with a temporary failure. While legitimate sending servers automatically retry messages on temporary failures, spammers rarely do. If the MailHurdle servers receive mail with the same sender and receiver information again within a certain period of time, a relationship will be recorded (and saved for a month), and the message(s) will be delivered to the appropriate user’s inbox. Every time another message with this same sender and receiver information arrives, it will be delivered immediately, and the mail relationship will extend to another month from that date.

Anyone who uses an “@umd.edu” e-mail address will notice some differences in e-mail delivery from this new software. In particular, the first time that a message is sent to you from a new sender that is outside the umd.edu domain, you will experience a delay in the delivery. The delay is dependent upon the sending server’s retry delay and could last from a few minutes to several hours. After that first message is delivered, messages from that sender will be delivered normally until you have a gap of over a month between messages. If there is a gap greater than a month, the first message after the gap will also be subject to the initial delay. However, all mail from UMD domain addresses, anything ending in “umd.edu,” is exempt from this delaying tactic.

While no system can guarantee the elimination of all spam, the university should see a decrease in the amount of spam entering our e-mail servers through the use of this software. For more information, please visit www.helpdesk.umd.edu/documents/4/4772.