Hello,
The test exchange server I'm trying to deploy passes all connectivity tests but is having trouble sending anything outbound. it can receive from the outside just fine. We've already processed our reverse delegation DNS request through our ISP and it's up and running.
Mail just gets stuck in queue and keeps trying to retry with the 451.4.4.0 error encountered while communicating with primary target IP addresses then ends up failing to send with the header #550 4.4.7 QUEUE.Expired; message expired ##