EWS API 2013 Calendar: The specified folder could not be found in the store

Question

With Exchange 2013 EWS API in C#, trying to create an appointment in the calendar of another user, as follows:

var mailbox = new Mailbox("[email protected]");
var folderId = new FolderId(WellKnownFolderName.Calendar, mailbox);
var appointment = new Appointment(service);
appointment....//etc
appointment.Save(folderId, SendInvitationsMode.SendToAllAndSaveCopy);

This works if we create the appointment via the administrators calendar, but not when we specify the account of another user that was created through the Exchange Admin Center (ECP). We get the error:

The specified folder could not be found in the store.

Apparently this is a permissions issue, but where is this permission set?

Answer 1

The user you authenticate with on the service object must have full access permission to the calendar you want to save the appointment on. This can be done via Exchange Management Console or PowerShell. There are alternatives, such as impersonation, but that requires slightly different coding.