reinstalled Exchange 2010 no user mailboxes

[imp_squared]

• Exchange 2010 was running on Win Server 2008 R2.
• Upgraded the DC to Win Server 2012 R2 - raised the domain functionality level to Win Server 2012 R2 (totally forgot about Win Server 2008 R2 on the Exchange.
• Exchange crashed, so uninstalled Exchange server and reinstalled Exchange, to try to start fresh.
• The issue - cannot recreate users as the Exchange server says the users already exist. (of course they do as I don't want to wipe out active directory) Can Exchange and How can I get this fresh copy of Exchange 2010 to recognize the existing users?

• I have the old Exchange 2010 database in working order - I know how to mount the old database and copy the old mailbox stores to new users when they are created.
• I've tired dial tone recovery - no luck - I'll be looking into this more.
• Would installing newer Exchange server help? Exchange 2013? 2016?

[#2 · Accepted solution]

UPDATE! Good news!

In the exchange management shell I ran Get-Mailbox

This returned a list of all the mailbox users from the old exchange server, but each user's mailbox had a warning on it "object corrupted and in an inconsistent state"

So I ran Disable-Mailbox to disable all the old mailboxes (this removes any old Exchange 2010 attributes in the AD user object)

After that I opened the exchange management console, go to create new mailbox, select existing users, browse and there we go all the previous users show up in the list for me to create new mailboxes for, into my new Exchange 2010 installation.

what next...

I'll recreate all the exchange mailboxes as needed for the company

mount the copy of the old exchange database as a recovery database

then I should be able to use Restore-Mailbox to restore the old databases into the new mailboxes for each user setup exchange and get it running again

[#3]

UPDATE! Final

I recreated all the exchange mailboxes as needed for the company

I created a new database, copied the old database over, rename the database to match the newly created database, mounted the database. All the mailboxes were in the "disconnected mailbox" area in EMC

Then I reconnected all the databases to the corresponding user accounts in AD and boom Users had access to their old mailboxes through Outlook on their computers in the office!

Now I just need to configure the Exchange server to send and receive email.

Point the DNS records correctly and it is working good now!