We recently went into co-existence mode and all seems well except for EWS. I am seeing some 200 responses in IIS logs for EWS requests but also Im seeing many 500 responses. Our cisco unity connection application, which relies solely on EWS now throws an error when it tries to access a mailbox on Exchange 2k7 when the request is proxied from 2K13 environment. It uses an account that has impersonation rights to all mailboxes in both environements. Any mailbox on 2k13 there is no issue. These are the errors:
ErrorNoRespondingCASInDestinationSite
Exchange Web Services are not currently available for this request because none of the Client Access Servers in the destination site could process the request.
I've gone over all settings with a fine tooth comb and everythings seems to be in place per MS guidelines. 2k7 internal and external EWS URLs are set to legacy.ourdomain.com. Any help is greatly appreciated.
Rich