I'm having a weird issue with the Exchange Web Services. The operation I'm attempting is pretty simple—pull a user's calendar items for the current week on our internal website. When testing locally, the ews managed API pulls the calendar information just fine. When deployed to the web server (using integrated windows authentication), it chokes. My trace is telling me that access is denied in the Exchange call.

Initially, I thought this was a double-hop NTLM permissions issue, but it turns out that the service actually works for some internal users, but not for most. The only thing I can find that the functioning users have in common is that they are blackberry users and I surmise that their exchange permissions are setup differently. Or are their active directory accounts setup differently? I don't know and it's driving me crazy.

I surmise that the blackberry app runs some scripts when a user is added to the application, but I'm completely unfamiliar with what may be going on behind the scenes there.

So. Is there a way to duplicate the permissions those users enjoy (either AD or Exchange permissions)? And/or how exactly does one fix the double-hop credentials situation?