To defend against a good deal of incoming spam, and to put pressure on these open relays to reconfigure their servers so they cannot be used as a tool for spammers, dragon.rutgers.edu, the server through which most email for the CS faculty servers passes, refuses email from open relays. Such email will be rejected with a message something like
Your message did not reach some or all of the intended recipients. Subject: RE: New Classes Sent: 2/18/02 5:40 PM The following recipient(s) could not be reached: 'Recipient Name' on 2/18/02 5:40 PM There was a SMTP communication problem with the recipient's email server. Please contact your system administrator. <originating.host.addr #5.5.0 smtp;591 your host is blacklisted by blacklisting.host.addr. Send your questions to firstname.lastname@example.org>As you see, the name of the failed recipient is identified as well as the hostname of the service identifying the sending system as an open relay. (Connecting to that host on the web and looking up the originating host address in their database will get you to a place to get further information.) And if all else fails, a local address is supplied for an end user to contact for further assistance.
"But someone cannot contact me now!" Suppose you hear from someone trying to get in touch with you. Perhaps they do not understand the message and/or do not know how to proceed. You can refer them to a more verbose, user-friendly explanation of what has happened and how to remedy things at http://www.cs.rutgers.edu/email-blacklist.html. They will also be directed to that explanation if they email the "questions" email address in the bounce message.