Mr

Can you explain to me why did you write Yours Faithfully and not Yours faithfully and also Yours Sincerely and not Yours sincerely?

[Hi_there_Carl]

The Complimentary Close and Signature Line The left edge of the close and signature line in a friendly letter begin in the center, at the same column as the heading.
The complimentary close begins with a capital letter and ends with a comma.


Skip from one to three spaces (two on a typewriter), and type in the signature line, the printed name of the person signing the letter. If the writer and reader are very friendly, or if the letter is handwritten in the same script as the signature, the signature line or the last name in the signature line may be omitted.


Sign the name in the space between the close and the signature line, starting at the left edge of the signature line.
Unless there is great familiarity between the correspondents, the signature should be in blue or black ink.

Example:

Truly yours, (Signature goes here)
Margaret Fong

[David L.]

Yours faithfully and Yours sincerely are the correct forms.

[Hi_there_Carl]

yes and there should be a comma following.

[rewboss]

Originally Posted by Hi_there_Carl

yes and there should be a comma following.

That's not always true. There are many conventions in use. One modern convention is to omit all punctuation in addresses (except apostrophes), the date, the salutation and the complimentary close of a formal letter.

[David L.]

I was drilled in primary school to put in commas after every piece of the address, after Dear Sir, and each element of the final salutation. Some years ago I noticed that the secretaries where typing my reports omitting all the commas I had carefully put in.
Boy, correspondence these days looks so much less cluttered without them!