@Michaelh The DAC is “Notification”. The To: field is Notification.NTo and the CC: field is Notification.NCc. The issue is that if you link either of those fields to the Document (PO, Invoice, whatever), the output will be something like ((Remit_Contact.Email)) which won’t be particularly useful. You won’t have this issue if you “hardcode” the user, which would look something like EMAIL((username));. If you do hardcode the user, you can get creative and link it to their User profile and pull their enabled status.
That said, if the user leaves the company, they likely won’t have access to their work email, and it would generally have been disabled. Assuming you’re sending this to someone at another company, this part is managed best via their Contact profile.