Have you made any changes to Office and Windows before this issue occurs?
Can you send/receive normally on the web mail?
Please check the connection status of Outlook client to see if it show “Connected” correctly.

Let’s repair account to see if it helps. To do this, click File > Account Settings > Account Settings. Select your IMAP account, click Repair.
If issue continues, we can test this in a new profile: Go to Control Panel > Mail > Show Profiles > Add. Follow the instruction to configure your IMAP account.
Any updates, please feel free to post back.
Regards,
Perry
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