If you rebuild a Microsoft Exchange Server and reconstruct mailboxes, your Outlook clients will notice this and give you two options: Connect to the Temporary mailbox, or Use Old Data. That cryptic option really means you can choose to connect to the new mail store, which will fail, or use the last copy of the old store.
The correct answer is usually Old Data. Go in, and then immediately back up your storage file by doing this:
1. File Menu
3. Advanced (in the left column)
5. Other File types
6. Outlook File (.pst)
7. Choose a visible folder, like the Desktop, and click Export. It may take a long time.
Then, you need to try and connect to the Exchange server. You'll need to get some new credentials, and this process is not reliable.
What's happened, basically, is that the new mailbox has a new GUID. So you need to tell Outlook to use it; to get access to it, you need to create a new user account. To do this, quit Outlook, then go to Control Panel and search for Mail (32 bit).
Mail is used to create and destroy email accounts for Outlook. So, what you're now going to do is create an alternative Outlook account. There are a few ways to do this, but I'll cover the simplest and safest. This will preserve the old account, and the old data file, in a different profile.
Set a name, and then set up the account.
Back in the Profiles dialog, set this profile to be the default one, and use it all the time.
Quit the control panel, then start Outlook. It should connect.
Quit Outlook and start it again. This will cause the cached exchange mode to work correctly.
You can now use the account. The other profile can be deleted. You might want to wait a month for the new system to stabilize before deleting the account. Also, deleting the account may not delete the data file - you have to find that manually and remove it yourself.
I had a problem with the Mail control panel. It was missing. So I found one in Microsoft Office\Office14\MLCFG32.CPL. It works from that directory. It didn't work when I copied it to Windows\System32. Probably need to fix the MSO install.