So, there’s yet another lesser-known feature of the new iPhone v1.1.3 firmware that we overlooked previously. We have already switched our Gmail account to IMAP, and configured our iPhone’s Gmail account accordingly, so we didn’t really notice any difference. But, to any iPhone v1.1.3 users that haven’t made the switch to Gmail’s IMAP service, you may have noticed that the Gmail email account is automatically setup as an IMAP profile.
Be forewarned, IMAP email accounts work differently from POP3 accounts. Any changes, including deletions, will be reflected on the server. If you move an email from one inbox to another, you will be moving that email on the server-side as well. If you delete and email, you will be deleting that email on the Gmail server.
Get the picture? Changes to your iPhone’s email inbox are no longer isolated from the server. Be careful what you delete, because they may just be deleted forever.
[Via: Google Help Center]