I’m a 16 months from retirement. instead of ‘Cheers’ perhaps I will use this 
I’ve been using “Cheers” for a decade or more, a habit I picked up by imitating a friend (another American) who uses it. It has spread from there - I was amused to note that several of my correspondents then picked it up from me.
It’s a great alternative to “thanks” or the weirdly formal “sincerely.” That’s probably why people glom on to it once they see it as an option.
a habit I picked up from our lawyer (professional setting) … he often closes the door in mails, etc… with the phrase:
“that is all I can contribute to this matter - best of luck with your (whatever)” …
that is a rather chalant version of… ok, now go fuck yourself .
Being a product of so many years of seeing rows of asterisks standing in for curses, swearing and the like, my first thought on seeing this was that it seemed very un-Mencken.