Autodiscover service overlap between Exchnage 2007 and 2013 mailboxes

Hi,<o:p></o:p>

I have Exchange 2007 Legacy environment and owa/rpc/activesync/autodiscover configured with DNS name owa.domain.com.<o:p></o:p>

I have installed Exchange 2013 and owa/rpc/activesync/autodiscover configured with DNS name mobile.domain.com.<o:p></o:p>

Its a requirement to retain different URL for Exchange 2007 and 2013.<o:p></o:p>

Now...Exchange 2007 users RPC over http is broken because their outlook rpc setting is automatically getting configured to mobile.domain.com which belongs to Exchange 2013.<o:p></o:p>

I know I have thought about updating the hostfile for Exchange 2007 clients to achieve this.Without changing the URL and retaining the existing DNS names, can we prevent RPC over https outlook setting changes for Exchange 2007 users alone?