As far as i can tell from searching this board and other qmail sites, the 10,000's of emails in my queue at the moment are actually bounce messages. Although the information i can find by searching is ambiguous and sketchy. This is how I understand the process. 1. QMail recieves an incoming mail from spammer to email@example.com. It accepts the mail because it is a valid domain hosted by the server 2. The randomname user in the address is not valid and so QMail bounces the email back to the return path address which is usually an invalid address as well, so the bounce message ends up in the queue for a week and thus they start to build up and clog the queue. Right now i understand that i can set a bounceall for all invalid usernames to a black hole address, however i have a LOT of servers hosting a LOT of domains and it is a big job to do this, not to mention the fact that if any of my customers turn it off again the problem will re-occur. And Surely there is a way to stop QMail from generating bounce messages at all, or better still, to generate an error at the RCPT TO: prompt during SMTP transaction instead of accepting the bad mail. There is something called RCPTCHECK kicking around, but it seems dreadfully complicated to setup. Bouncing to black holes and/or disabling bounce messages is all well and good, but it's still wasting the server's bandwidth by accepting the mail in the first place.