Well, it took me a couple of hours to figure out that Gmail had a great joke going.
They would send you through regular mail, any email, on paper, that you want to get a hard copy of.
I kinda thought it was cool, for a while.
But then the date dawned on me, and there you go, April Fools.
Below is a copy of their information page with all the data on the "Cool idea."
It was a good one. Nice job Google.
(Click to enlarge)