Please follow the steps below to fix the problem:
- Click File and Account Settings.
- Click Account and then Change.
- Click More Settings and then the Connection tab.
- At the bottom, click Exchange Proxy Settings.
- Click the check box that says "On fast networks, connect using HTTP first, and then connect using TCP/IP.
- Click Ok, Ok, Next, Finish, and then Close.
- Close Outlook and reopen it.