Doing my matura (sort of like the SAT's) I took advance level English just so I could get away from having to know how to properly write an English letter. I got a 98.5% and to this day (~6 years later) I couldn't tell you how to properly format something that is officially recognised as a Letter.
Email has thrown most of the old rules about addressing people out the door. Nothing I learned in elementary or middle school about written communication is even remotely useful these days. The only times those things even remotely come in to play are when I have to write a formal letter to the government.
And even then I just google the correct format.
Except if you're sending encrypted e-mails :)
In that regard a colleague and I now use an incrementing integer for the subject, with occasional skips in the sequence.