You've Got Mail. Or Have You?

Letter writing was such a huge deal in school! I wonder if the teachers and other authorities realized that in the real world, we would hardly ever write letters, leave alone use any of those formats we were taught.
English grammar exams demanded that we knew the format of both formal and informal letters. Here's what I remember:

FORMAL LETTER

INFORMAL LETTER

I'm not sure how many people write actual letters any more. Written communication seems more like this:

FORMAL

 INFORMAL

(This is based on the assumption that the writer uses spacing at all)

Or more commonly seen...

You know, people are right when they say that you learn all the important things in life when you're in kindergarten, or elementary school at the most.