Hope you can help :)
We have 3 Exchange 2013 Mailbox Servers as part of a DAG, each server has it's own NAT rule to send mail out via smart host (message labs)
Each host needs to be added into Message Labs to be part of an "Authorised outbound IP Address" list to send mail to them, we removed 1 of them as a test and mail was held in the queue with the error "open relay not allowed" which was expected... however I had to run the PowerShell command "Redirect-Message" to forward mail out of another MBX server.
Is there anything I need to configure so the mail will auto retry out of one of the other MBX servers in the DAG? I thought the shadow redundancy queue would of sorted that but maybe I'm wrong....
Hope that makes sense!
Many Thanks :)