You did make me laugh with this because I have done just that 
after reading the posts before yours, I went to dash and looked at my orders as I knew that I had 2 older ones that I had not marked as posted that were up the top and when I clicked to see order there are two places where it says mark as shipped, one in the yellow bar at the top and the other underneath the address in the white bit so I thought maybe if I click on that one instead of the one above it might not send them a email - but probably not ha ha , so I’ll let you know if I get a confused email from the customers! 
