Is DistinguishedFolderId 'inbox' guaranteed to exist?

Question

In Exchange Web Services we used to check connectivity by looking for the 'calendar' DistinguishedFolderId for the logged in user: What is the simplest EWS call to test connectivity? .

Our synchronization codes relies on calendars being shared with that logged in user (delegate access).

We found out that the logged in user does not necessarily have a 'calendar' DistinguishedFolderId. It looks like admins sometimes forget to create a calendar for that user (?). For the synchronization this is not an issue, because nothing needs to be accessed in that users calendar. But the connectivity test fails because of this.

I have now switched to quering DistinguishedFolderId 'inbox' using GetFolder for the connectivity test (and still look up 'calendar' for all the users that need to have their calendars synced).

But this brings up the question:
Is DistinguishedFolderId 'inbox' guaranteed to exist for an Exchange user?

We are talking about Windows AD users.

Answer 1

Default folders, such as the Inbox folder, can't be deleted.