Enhanced non-delivery reports (NDRs) in Office 365
Regardless which email system or service you use, when an email message you send can’t be delivered you’ll receive a non-delivery report (NDR), also known as a bounce message. The NDR will tell you the message wasn’t delivered, but after that it’s mostly technical jargon designed more for computer science professionals than for the typical email user. You’re often left to fend for yourself to try to fix the issue, searching the web and posting questions on forums for clues to what’s going on and, more importantly, how to fix it. While advances in technology over the last 30 years have been immense, the state of the art in NDRs is still just an homage to 1982—overly technical and ill-designed for the modern email user. But that’s about to change.
Read more at source: http://blogs.office.com/2015/04/17/enhanced-non-delivery-reports-ndrs-in-office-365/