http://blogs.msdn.com/b/webdav_101/archive/2012/06/27/the-importance-of-ews-impersonation-while-using-an-application-account.aspxDevelopers of applications which require access to user mailboxes often struggle with the choice between the Impersonation and Delegation access methods. While both provide programmatic rights to mailbox objects, they are designed to meet rather differentenTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)