• Backscatter
  This page contains some advice for anyone who is receiving unwanted non-delivery reports as a result of a spammer's activities. 'Backscatter' is the name given to messages that are generated when a spammer uses your mail address or an invented mail address at a domain that you own in the 'From:' line of their messages. If the spammer's message can't be delivered for any reason, the receiving host will send back a non-delivery report to the address in the 'From:' line.
  in Software > Malware Protection with email spam
• UMIACS IMAP Spam filter
  in Organizations > U Md > UMIACS with email spam umiacs

spam from all users