Kenny, I love that new feature in O365. However, we still use an email account hosted on a separate email server / service for delivery confirmation. By using a separate server, you can confirm that the email actually left your mail server and was released to the wild. I know it sounds like one step too many but the school of hard knocks taught me that having a way to prove every step of the delivery process within your control helps 1) confirm the process for your own peace of mind (and to the customers IT team) and 2) provides extra fodder when a customer pushes back and contends the message was never sent. Is it fool proof? No. Will it remove every argument a customer will make? No. Does it give you stronger ground to stand on when addressing disputes? In our case, it absolutely has.