When executing an Exchange SmartObject method via an activity in a workflow, the workflow will go into an error state.
The error message will be similar to the following:
“Service: Exchange Severity: Error Error Message: ExchangeIpersonation SOAP header must be present for this type of OAuth token. InnerException Message”.
Exchange SmartObjects in a workflow are run using the email account configured with the service instance and not under the email of the person running the workflow. If the workflow, for example, creates an appointment, the appointment will be created from the account used when activating the Exchange Feature and not from the email of the person running the workflow.