We have three physical office sites each connected to the internet with T1's and have VPN's running between each of the offices. We currently use Office 2003 Standard with an ISP pop3 solution. We need to implement an Exchange environment.
Site 1: 18 employees
Site 2: 5 employees
Site 3: 2 employees
Each site has its own DC with Site 1 having two. Each runs it own site in AD and DNS. The question I have is would it be better to implement ONE exchange server at Site 1 and just have the others connect over the VPN (btw, site 1 and site 2 will have a private T1 line installed shortly)? Or is it better to run an Exchange server at each site and get into multiple server sync issues?
I'd appreciate any additional background on the pros/cons of each.