I got this error after moving someone from a local Exchange 2003 server to Office 365.
When you open outlook you will get a message saying:
The file C:\Users\<username>\Local\Microsoft\Outlook\<emailaddress>.ost cannot be accessed because it has been configured for use with a different mailbox.
From what I can figure out it is because it another exchange account with the same name but different credentials and on a different server but still using the same profile so outlook tries to use the same OST file.
How to fix the OST cannot be accessed error
To fix this issue what you need to do is configure a different email profile. To do this follow these steps:
- Open Control Panel
- Select Mail
- Select Profiles
- Add a new profile
- Give the profile a name and hit OK
- Then connect your email account using the correct credentials
Now when you open Outlook it should sync up with Exchange or Office 365.