If you just installed Exchange 2013 and you have an Exchange 2010 mailbox you cannot access EAC you get the old ECP management

If you just installed Exchange 2013 and you try to go to http://ServerName/ecp you’ll notice that you get the old Exchange 2010 interface and cannot manage your Exchange 2013 server.  There is a simple fix for this just simply use the following url syntax.
https://ServerName/ecp?ExchClientVer=15