You must get this error because of incorrect port numbers here is how to solve it:
If you haven't activated encryption, update the incoming server port to 143, or set the port number to 993 if you have. To do so, take the following steps:
1. Go to File > Account Settings > Account Settings in Outlook.
2. Double-click the Email Account in the Account Settings pop-up window.
3. Select the More Settings tab in the Change Account pop-up window, then Advanced.
4. In the Internet E-mail Settings box that pops up, select the advanced tab and change the Incoming server (IMAP) port number to 143 (if SSL isn't enabled) or 993 (if SSL/TLS is).
5. To save your changes,
