We hired a consultant to setup a new Exchange implementation and he has it set up on its own messaging domain. It is running Windows server 2012 with Exchange 2013.
We have an existing Active Directory where user log in and have their mailboxes on an exchange 2007 implementation. The Active directory was windows 2003 R2 but I recently ran adprep to bring it up to 2008 schema and added a windows 2008 domain controller which also runs all of the operation master roles.
The consultant told me there is no way to integrate these AD domains so that users have a single signon through our original AD but access their mailboxes on the new 2012 AD/2013 Exchange. I cannot believe that this is the case.
Is there a best practice setup or way to integrate these so that I can migrate mailbox data and then just point the accounts to their new mailboxes?