Some GUHSD employees have been alarmed by messages in their inboxes which suggest that a message they sent was blocked by the Barracuda spam filter. This article explains what is happening. Your email address is like a germ on the doorknob of the Internet.  Whether intended or not, it is passed by a variety of mechanisms, both active and passive.  There is nothing you can do about this. Spammers virtually never indicate their correct return address because they wish to penetrate loose spam protections and avoid becoming blacklisted. They will instead substitute someone else's address (yours).  This is called spoofing.  They usually acquire your address from lists harvested by viruses, phishing, spambots, etc.  Never mind what these terms mean; just think of them as electronic fly traps that grab your address.  There are things you can do to reduce how likely and how often your address is used but, short of returning to a Stone Age existence, it simply can't be avoided. When a spammer sends a message as though it's from you, most spam filters can still detect that it's junk and discard it.  Many by default bounce the message back.  Unfortunately, too many filters bounce the message back to the spoofed From address (you), not the real sender.  These misdirected bounces are called backscatter. When you receive a message indicating that the Barracuda Spam Firewall has rejected a message you sent, this is backscatter from some other organization's Barracuda, not GUHSD's.  We have temporarily set our spam filter to not bounce blocked messages and create backscatter for others.  This means that someone who sends you a message that is rejected, will not know that it has been rejected.  They will just think you are rude for not responding.  This is painful but necessary as backscatter can land us on blacklists, meaning that messages you send from Groupwise might be rejected as spam by parent and education email systems.  (We've experienced this at least twice in the past with AOL and Cox and it's a pain in the neck to get our domain off of a blacklist.)  We are working with our spam filter provider to determine ways to reduce backscatter received and restore bounce notification without risking blacklisting GUHSD. What can you do? If  the "bounced"  message does not appear to be from a someone you recently sent an email or does not bear a subject you recognize as having composed, simply delete it.