When attempting to run an Exchange Internal Delivery test against a whole Organization which contains a Disaster Recovery (DR) server it fails
DR servers are simple backup places for passive database copies for restore purposes. They are not real mailbox servers participating in the email flow. Therefore they should not be a valid target for the Internal delivery test.
Remove DR severs from the Exchange Internal Delivery test.
Enhancement Request TF00186680 has been raised to include functionality of automatically removing Disaster Recovery servers from Exchange Internal Delivery tests when set against a whole organization