We just migrated to new servers in a Server 2012 and Exchange 2013 environment running the Office 2010 Outlook client as well as the 2013 Exchange OWA. Using Queue Viewer I can see messages moving through the "Mail1" server. When I connect to the "Mail2" backup server, that queue is backlogged at the times when we know we have a problem. We start/stop the transport service and the MAIL2 queue clears.
Sometimes when we first access the Queue Viewer we get the message "The remote pipeline has been stopped...".
Any suggestions on where we might look to see what is stopping the transport to avoid the manual stop/start?