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Information Technology

Information Technology


Blacklists block Spam

Blacklists are used to prevent spam (junk email messages) from entering an email system. At Rice, several blacklists are utilized to reduce spam traffic in the university's email system. All Rice employees and students benefit from this blacklist service, but anyone who is concerned about missing important messages can opt out. Just remember that spam and phishing (email identity fraud and theft) messages make up 80-90% of all messages addressed to rice.edu email accounts.

How do Blacklists work at Rice?

At Rice, using a blacklist service means that the sender's address for every incoming email message is compared to several open-source organizations' blacklists and messages are accepted or rejected by the Rice email system based on where the message originated.

Here's how it works inside the hedges:

  1. Open source organizations use databases to track email servers that send spam messages or that are set up (configured) in such a way that they can be hijacked by spammers or used as a front for spam or phishing agents. These organizations publish suspicious server addresses in blacklists.
  2. A software application protecting the Rice email system compares the sender address on all incoming email messages to addresses on the blacklists.
  3. When an inbound email originates from an email server found on multiple blacklists, Rice refuses to accept the incoming message and returns it to the sender with an explanation* of why it was blocked.
  4. Alldepts, pres-fac, and other Rice-originated email messages do not go through the blacklist service because the messages originate within the Rice system and not outside of Rice.
  5. Spam identification tools such as DSPAM and Spam Assassin continue to rate the content of messages within the Rice system, placing ***SPAM*** tags on messages that have a high probability of containing junk mail. These tools cannot stop the delivery of messages and are not connected to the black list service in any way.

*Sample Message included with Email messages rejected for blacklist reasons

550 - Your email to Rice University was NOT delivered. Please use another communication method.

Rice University blocks messages from email services that are listed as sources of large numbers of broadcast SPAM messages. Your email was blocked because it was sent through such a listed email service, or was mistaken for such an email.

You should contact your intended recipient through some other means, and let him or her know that your message was blocked for this reason. He or she may be able to have your email server removed from the list of blocked email services, if it was listed by mistake.

In addition, you may want to contact your email server administrator to try to resolve this problem for future messages.

If your message is critical, contact the Rice IT Help Desk at 1-713-348-4357.

Can a legitimate mail server get off a blacklist?

Yes! When a client on an blacklisted mail server receives a mail rejection notice due to a blacklist reference, the administrator can correct their servers' configuration and then work with the blacklist manager to remove this server from that blacklist. 

 Last updated: July 13, 2010 by: Carlyn Chatfield