We currently have exchange 2003 running on server 2003, and domain controller running on server 2003. We have installed a server 2012R2 and running as a domain controller as well. We will be installing exchange 2013 on server 2012R2 and migrating to that. We are in the process of moving all the shares off the 2003 domain controller as we can not install exchange 2013 until that is shut down. My question is, can we use exchange 2013 tools on our server 2012R2 domain controller to connect with exchange 2003? Currently when we add a new user on our 2003 domain controller we have the option to create a mail box for them, we would like to continue to do that until we are able to completely move to exchange 2013? I know this might be confusing so please let me know if you need any other information.