Hello,In my company we currently have 3 exchange servers in a single AD environment. All exchange servers are independeant and are not connected in anyway. the issue i am facing is we are in a MPLS network which means our own private network. we have three sites connected to this and each site has a backup internet line just incase the MPLS fails.The issue is when the MPLS goes down (in one location) we can send and recieve email internally and externally, but when the Internet goes down we can only send email internally. is there anyway we can use the other exchange servers to relay the external email through?e.g. if London internet goes down we would like to route the London external email through the US exchange server?please help with this matterthanksHitesh

It is not possible to have multiple Exchange servers in a single AD enviroment, and them not be aware of eachother. Exchange 2003 uses link-state routing, so to predict how messages are going to flow, and to prevent failure, see here for understanding your design considerations. If you need more help, please post back the routing group configuration you are currently using. Exchange 2007 does not use link-state or routing groups. Mail travels across hub transport servers based on cost. See here for more detail on that.