My customer runs SBS 2008 (with Exchange 2007), and would like to migrate to a new DC, file server, etc, along with Exchange 2013. However, a number of this customer's employees connect to the Exchange 2007 server while they're away from the campus it physically resides at, via Outlook Anywhere (on laptops) and ActiveSync (iPhones, iPads, Android phones and tablets).
The URLs for the virtual directories for Exchange will be set so that all of them, internal and external, point to mail.OurDomain.org. This will remain the same whether we have the old server or the new one. However, when configuring both Outlook (see screenshot) and ActiveSync clients, a mail server's hostname must be specified--current users are configured to access "OldServer", but we'll be moving to "NewServer". Once the old 2007 server is removed, and only the new 2013 server remains, will OA and ActiveSync users be able to connect to their mailboxes seamlessly, without needing to reconfigure their connection settings, or will we need to help every off-campus user redo them?
I realize Exchange 2013 can be configured to proxy and pass requests for older Exchange servers to those servers--we will be removing the old Exchange 2007 server almost immediately, so this isn't an option.