The difference between British and American spelling
To a British English American EnglishMan (unknown) Dear Sir Dear Sir
Woman (unknown). Dear Madam Dear Madam
Person:name and gender unknown) Dear Sir/Madam Dear Sir/Madam
Man Dear Mr Johns Dear Mr. Johns
Woman (married or widowed) Dear Mrs Johns Dear Mrs.Johns
Woman (unmarried) Dear Miss Johns Dear Miss Johns
Woman (marital satus unknown) Dear Ms Johns Dear Ms Johns
MArried couple Dear Mr and Ms Black Dear Mr. and Mrs. Black
Friend Dear Peter Dear Peter