Testing email deliverability fails to Microsoft ESP domains for some specific IPs
|Knowledge Article Number||000232927|
|Description||The email deliverability testing functionality sends emails from the organizations data center and backup data centers to a users email address to test deliverability. This helps test a variety of email scenarios to the users email address. Included in this test is mail sent from the IPs of MTAs that are only used specifically for email relaying.
Microsoft hosted email domains may filter out mail from some of the IPs addresses used for email relaying. This example of filtering is generally based on the IP reputation aspect of the Microsoft filters as the IP addresses of these relay MTAs send little or no mail to Microsoft hosted domains so can have a low reputation with Microsoft in general
Three IPs that seem to be particularly affected by this are the specific email relay IPs
If your organization is not using email relay functionality please disregard these failures.