If you are not using letterhead, type your street address, city, and ZIP code in the upper left hand corner of the page. Type each address fact on its own line, as if addressing an envelope. Skip one line and type the date, spelling out the name of the month and using a comma aft...
spelling, pronunciation and capitalisation, so if you wanted to be mArK, I would respect that and address you as such (it would also have the advantage of making it clear I was addressing you, not any of the other Marks around).