Dear,

in which way you r making connection between the newly moved LAN and to ur mail server.Any firewall kind of thing inbetween the mail server and the lan which is moved as u said.

if the client is in the same ip wing there will not be any restrictions in between the client and the mail server.So there will not be any problem.But if y change the ip wing of the cleints it is not the same like the previous one.

Let me know how u connected the newly changed lan with the server,..


regrds
prabu