How can the Administration review all envelopes sent by all Users?

An Admin can share any user's folders with any other user. So the Admin could share every user's folders with themself. They would then be able to go into any user's folders and look at their envelopes. Learn about setting up and using Shared Envelopes.

As an Admin, you also have the ability to generate Reports for all user's envelopes which may provide all the information you need. But this doesn't allow you to see the documents or open the envelope to examine the details fully like the Shared Envelopes would.