Many businesses still use a copier or multifunction device that has the ability to scan to email. Some units also allow a fax to email forwarding service. Unfortunately, many of these devices rely on some form of internal SMTP service to enable them to relay emails to recipients. If you have moved your exchange server to a cloud service this is no longer possible. However, These blog posts may have the answer.
How to set up an Internal SMTP Service for Windows Server 2012 Essentials