Today I spent a fair amount of time debugging this, first I added an option to very aggressively log any email failure
Once that was done I deployed and turned it on here, I have been trying to reply to this very topic by email and kept on getting that message.
When I looked at the log I saw nothing ...
So ... the process running this site were not even getting the messages, where were they going ??
Well, elastic is an enterprise customer, they have a staging instance with all data and settings, the staging instance has been polling email ... and it has reasonably old data.
I went ahead and disabled polling there, however... this leaves me wondering, do we even want to keep running this staging instance @nik9000 / @dadoonet are you using it for anything?