I'm having this issue with my Gmail on the iPhone. It autochecks, receives a new message, downloads it, and does the "new mail" sound. But then if I go into the Mail app to look at it shortly after the sound, the message disappears. It then autochecks, downloads the same message again, and gives the sound. This seems to be pretty consistent, I very often notice hearing 2 "new mail" sounds and then only see 1 new message. I also don't know if this is a 3.1 thing, because I don't recall this ever happening before a few weeks ago. Any thoughts? Edit: For clarification, I am using Gmail over IMAP, not Google Sync/Exchange.