If re-adding the IMAP account doesn't resolve the issue, you can try the following method: Check IMAP Folder: - After setting up your IMAP email account in Outlook, right-click on your email account and select IMAP Folders. - Click Subscribed and click Query. - Select all items in the list. - Select all tabs to sync the folders you wish to sync, including Drafts, Inbox, Junk, Sent, Templates, and Trash. - Uncheck the option "When displaying hierarchy in Outlook, show only subscribed folders." - Reboot Outlook and check if the error is resolved.