Keep me posted

Thought of the day. I have so few, bear with me.
I found it funny and ironic - and not to pick on @poploser - that the expression 'keep me posted' still exists.
I can't readily find a reference, but I would suggest it's related to the military sense of 'keeping your post' and things like the Pony Express.
The fact that we interact with each other in real time, virtually, and have these nifty little devices that permit us to access information on the fly, means that we're always informed, if we choose to be. Perhaps, too much.
Remember letters and cards? That you had to write on, put a stamp on, and walk to the post box? I can't remember the last time I posted a letter.