Setting a delay on all emails sent

Hi all,

An interesting one for you out there. We have a law firm as a customer and they would like to delay all emails sent so that there can be a final check before emails leave that confidential material is not going to the wrong person.

Does anyone know if it's possible to configure Exchange 2013 to automatically delay all messages for all users in their outbox. I know it can be done per message but what about globally for all messages.

Alternatively, any other options to achieve what they want?

Thanks,

Richard