Agree with RES-can: if used at all, the plural of "Madam" in a letter is "Mesdames" in BE as well.
Just my 2p on this - I agree with opalo's posting Wed Apr 5 12:38:59 2006:
the conventions are
"Dear Sir or Madam" "Dear Sir/Madam" in BE/AE
"Sehr geehrte Damen und Herren" in German
To write either one the other way round is unnecessary - no educated, emancipated woman is going to be offended by the word order - life's too short for such trivia.
If I receive a letter starting "Dear Madam or Sir" / "Dear Madam/Sir" I think either
1) "Oh dear, a direct translation - doesn't know the conventional greeting"
2) "Oh dear, someone's TRYING to be politically correct..."
(truly no offence meant, AndreasS - *I* now know that *YOU* mean it as a courtesy from a gentleman, but remember that the person receiving a business letter probably doesn't know the person who sent it, or what his/her intentions were...)
And on that note <@Doris SCNR>:http://www.cyberslayer.co.uk/jokes/joke0815.html