As part of my testing MailDroid 1.82, I also had the Android built-in mail app running too. Got a couple of messages and viewed them in the system mail app, then deleted them there. Went back to MD, messages still there, of course, showing as unread, so I did a refresh in MD. It started a sync, but then threw a 404. I would have expected it to simply remove any properly deleted messages from the display rather than show an error, regardless of where they were deleted, on the desktop, or another app. HTC Evo 4G on Exchange 2003 server.