Create a new identity in Office for Mac 2011 and rebuild Outlook data base and verify the status.
Follow the steps below to create a new identity:
1. Make sure Outlook 2011 for Mac is closed.
2. Click on Applications and then on Microsoft Office 2011 folder.
3. Click on the Office folder
4. Open the Microsoft Database Utility
5. Click on the + symbol
6. Give your identity a name.
Follow the steps in the KB below to rebuild Outlook database
Refer to the link below for more information: