From arnodelorme@gmail.com@21:1/5 to All on Thu Mar 9 10:38:19 2017
I have done some testing using my Gmail account on Mail OSX (offline) moving a message to one of my Gmail folders, and then using my phone to move the same message to the trash.
Upon connecting my Mac to the internet, the deleted message disappeared from the folder I had move it to. So the online version took precedence. Makes sense. There was no warning message though.