Polite phrase:      Dear Sir /Dear Madam

Dear Mr+nom /Dear Mrs +nom

Introduction :I’ve just received your letter…

Many thanks for your letter of April 11th

In reply to ..

Please find enclosed…

Closure of letter : I look forward to hearing from you

I should be grateful for an early reply

 My kindest regards.

Polite phrase: Sincerely yours.

S‘utilise davantage avec une personne que l’on a déjà rencontré :Faithfully yours

Best regards,