I have a central office site and I would like to know if it is considered acceptable to install Exchange 2010 CAS/Edge-Transport roles on VPS(s) in external datacentre(s) with a VPN back to our HQ where our mailbox and hub servers are.
My main goal is to have mail queued should the main site go down due to a local ISP failure.
Would there be any issues with this design and anything to be aware of?