1. Check your device settings and internet connection.
2. Make sure Outlook is up-to-date and is compatible with the version of the Operating System(OS) that is installed on your device.
3. Clear the cache on your device, restart Outlook, and log into the mail server again.
4. On the Outlook toolbar, click on ‘Send/Receive’ > ‘Download Headers’ and wait for the mailbox to be synchronized. If the issue still persists, move on to the next step.
5. Perform the ‘Repair’ function available under the ‘Help’ menu in Outlook.
6. Close Outlook and delete any .tmp files from the device. Reopen Outlook and try to access the mailbox again.
7. Create a new profile, using the Outlook mail interface, to access the email account.