Why doesn’t Outlook show new messages immediately?
We occasionally receive reports of a problem where Outlook is set up to check messages using an IMAP connection, but doesn’t show newly arrived messages promptly. They eventually appear in the Inbox, but it can be minutes or hours after they’ve already been delivered and are visible in other programs and Webmail.
This seems particularly common in Outlook 2013 and Outlook 2016 on Windows.
In these cases, removing and re-adding the IMAP account in Outlook usually fixes it. Since IMAP mail is stored on the server, not in Outlook, you shouldn't lose anything when doing this. Outlook should simply show exactly what was there before. (But of course, always make a backup before deleting anything on your computer, just in case.)
Note that we’re only suggesting removing and re-adding the “account” in the Outlook program settings. Don't delete anything on our servers.