Several users have reported an issue in which the iPhone's Mail app refuses to retrieve new messages from IMAP and POP servers after the OS 2.1 update. In these cases, the progress indicator will spin indefinitely, but no new mail appears. Or, the retrieval process appears complete, but no new mail appears.
As described by one iPhone Atlas reader:
"There seems to be an issue with the new 2.1 firmware and IMAP mail connections. The IMAP account will check mail, go through the process but not update the folder you are viewing (even when there is … Read more