Office 365 received the message that you specified. Unfortunately, we couldn't deliver the message to the recipient ({0}). ...

Office 365 received the message that you specified. Unfortunately, we couldn't deliver the message to the recipient ({0}). We couldn't deliver the message because Office 365 can't get the MX record for the recipient domain DNS. This usually happens when the domain's MX record isn't configured correctly. After we tried delivering the message for 48 hours, the message expired. Details are in the following section.