168 Trent Avenue
Newark NG6 7TJ

17 March 1995

Joanna Barker
54 Cedar Grove
Brighton BN1 7ZR

Note the position of the date, and note that the date requires no punctuation.

In British English, the greeting is always followed by a comma:
Dear Esther, or
Dear Mr Jackson,

In American usage, only a personal letter takes a comma here, while a business letter takes a colon:
Dear Esther, but
Dear Mr. Jackson:
If you are writing to a firm or an institution, and you have no name, you may use the greeting Dear Sir/Madam.

The closing always takes a comma:
Yours lovingly, or
Yours faithfully,

Note that only the first word of the closing is capitalized. In British usage, it is traditional to close with Yours sincerely when writing to a named person but Yours faithfully when using the Dear Sir/Madam greeting, but this distinction is anything but crucial. American usage prefers Yours sincerely or Sincerely yours (A) for all business letters. Things like Yours exasperatedly are only appropriate, if at all, in letters to newspapers.

In a personal letter, of course, you can use any closing you like: Yours lovingly, Looking forward to seeing you, It's not much fun without you, or whatever.© Larry Trask, 1997
И еще об английской пунктуации, бо она все-таки существует! - www.sussex.ac.uk/informatics/punctuation/essays...