EWS Managed API: Impersonation of users from several servers in the same domain

Does anybody know how impersonation 开发者_Go百科should be configured or if it is even possible for such configuration:

• Two (or more) servers ExchangeServer 2010/2007 (can be the same version can be different, depends on our clients environment).
• ONLY ONE "service account" located on one of these servers. this account has impersonation enabled and range of users is set for all users in domain (so in theory all users from all servers)

For now it seems that we need "service account" on each of servers to successful impersonation of users. It means that if we have 15 servers we need 15 service accounts which is pretty shitty situation and requirement for our customers.

Without service account dedicated to each server we get exception saying "The account does not have permission to impersonate the requested user". That means that we either set our impersonation the wrong way or impersonation does not work between servers.

Anyone has any thoughts on this subject? Any help or hints would be appreciated.

EDITED

I tested configuration where both servers are Exchange 2010 and impersonation works for users from both servers with one service account located on one of these servers. What is even better it does not matter which address (to what server in our environment) we set on ExchangeService object as its Url property, it still works.

So, now we suspect that problem originates from different user right model for 2007 and 2010 version of Exchange. But why it does not work even if 2007 has proper configuration of impersonation it still remains mystery.

Take a look here: http://blogs.msdn.com/b/emeamsgdev/archive/2011/08/12/ews-impersonation-in-a-mixed-2007-2010-environment.aspx