Before I start to spend lots of money on consultants, just wondering at a high level, what would be the best way to run two Exchange servers so if one goes down, then I can have MX records changed and have all e-mail route to the secondary server?
Given the lowish volume of e-mail that flows through I thought I could do one large replication of the Exchange stores first and then keep them in sync (by whatever means that are available) via a site to site VPN. That would save on WAN costs.
I do recall when we were migrating from one service provider to another, we ran two Exchange servers with one primary and one secondary at each DC and we slowly migrated mailboxes from one to the other. However all mail did go out and come in via the one external connection and Exchange knew where the mailboxes were located. However if the main Exchange server went down, then even with MX record changes etc. those who had mailboxes on the main server would be out of luck. So that wouldn't work but I suspect Exchange 2010 is a bit more capable in that respect.