If it is a business letter you would always type Yours faithfully at the end whether it was addressed to Dear Sir/Madam or Mr or Mrs. Also with a business letter the individual or the company's address should shown at the left hand magin. If it is a letter of a personal nature it would be Yours sincerely or other Kind regards, Love or whatever. Often in bussiness a person could be writing to a colleague who is also a friend and although on headed paper may start the letter - Dear Jim or whatever so you would in that instance type Yours sincerely unless the dictator used another term. also the s in sincerely and the f in faithfully should be lower case if it follows Yours.
——from Yahoo...