After installing some new Exchange 2016 servers, while testing the environment for mail flow, I noticed that I could not connect to the queue on any of the servers due to a failure to connect to the Transport service. I thought this was odd, as each server was a fresh install of Exchange. Here is the error message I saw when running the Get-Queue
cmdlet on the new servers:
I did as the error message suggested and verified that the Transport service was in fact started.
I was not able to find any information as to why this would be happening, and as a last effort, I thought I would change the Log On account for the Transport service to Local System to see if the issue was coming from there.
To make that change, I opened the Services application on the server, found Microsoft Exchange Transport in the list, right-clicked and selected Properties. I then went to the LogOn tab and changed the account to Local System...
...and it turns out that was the cause of the issue after all. After this change and a restart of the Transport service, mail began flowing and I could access the queue!