Try removing the account and then add it back. The steps below would help you to remove the account.
1. In Outlook, on the File menu, click Info > Account Settings > Account Settings
2. Click on the MAPI account and then click Remove
3. Click Yes to confirm that you want to remove the account.
4. Click Close
Now try the following steps to add the account into outlook
1. Exit Outlook.
2. Download the Microsoft Office Outlook Connector.
3. When prompted to open or save the file, click Open.
4. When prompted to run the software, click Run.
5. Follow the instructions on your screen to complete the installation.
6. The next time you start Outlook, you are prompted to configure the Outlook Connector. Enter the following information:
Your e-mail address, Your password and Your name as you want it to appear in the receiver's Inbox
7. Click OK.
Here’s to Good Karma