Thought I'd share this tip with the crowd... The chkuser patch, which ensures an address is valid in the given domain before accepting a message, would be defeated if you simply replace your vdelivermail line with a Maildrop delivery line in .qmail-default.
After taking a peek at how the chkuser patch works, I realized that it will work correctly if you instead comment-out the vdelivermail line and add your Maildrop line after. #| /home/vpopmail/bin/vdelivermail '' bounce-no-mailbox | maildrop .mailfilter Chkuser sees the "bounce-no-mailbox" it needs to see this way, without altering the patch. A little klugey maybe, but it works. - Ron