Well, I’m afraid that there are many reasons mail could bounce. In fact there are so many ways it could fail that sometimes I’m amazed that it works at all. But it definitely works most of the time, and one of the ways it works is that very bounce message you get.
You see, there’s gold in that bounce message. It’s not only telling you that your message didn’t go through, but if you look a little closer, you’ll see it’s trying to tell you why.
Bounce messages can vary in format, and in exact wording, depending on the mail server that’s sending the message back to you. Different types of mail servers use different terminology. Some are quite geeky and difficult to understand. Others seem to take five paragraphs to tell you that you probably just mistyped the email address you were sending to.
Include a copy of your bounce message and I will help you understand it.
Start by Checking the MX records for the domain that you want to use and ensure that they are ALL pointing to the Exchange server. It is not unheard of for hosts to leave their own servers in place.
If you know who is sending you email and getting rejects then ask them if they use the same host that you do. Most ISPs systems are setup to presume that they are responsible for everything connected to a domain and cannot cope with a setup where another server deals with email.
The verification failure might be down to non-matching reverse DNS records. Have you confirmed that reverse DNS etc is configured correctly?