I've got a customer who reported yesterday that they have customers reporting that they are receiving duplicate emails from them. I checked in out outbound mail appliance (Barracuda) and indeed see this. I am looking at the spool in smartermail now and see a correlation. I have a message that has been in the Spool for 3h 14m and has been attempted to deliver 4 times and has actually been delivered 4 times and it still has a status of waiting to deliver. I'm running 15.2.6039.