Dear sirs... gen.

[Mutarjim]

Дамы и господа! Вопрос простой, и наверняка он уже не раз обсуждался в темах деловой переписки.
Как обращаться в деловом письме, когда:
а) я пишу на общее мыло и точно знаю, что на него завязаны и мужчины, и женщины?
b) я пишу на общее мыло и точно не знаю пол адресата
с) когда я пишу двум людям (мужчине и женщине), либо на разные адреса (кого-то в копию), либо на один их общий, и мне, в принципе, не важно кто из них ответит - Джон или Мэри?

[Nevazhno kto]

а) Dear Sir or Madam
b) Dear Sir or Madam
c) Dear John and Mary

[posekretu]

a) Dear all,
b) Dear Sir/Madam, Dear (должность)
с) Не важно, кто стоит в копии, в письме обращаются к прямому адресату.
Если общий ящик, то Dear John and Mary.

Вообще, все зависит от степени официоза, и от того, в каких отношениях Вы с теми, к кому обращаетесь.

[Mutarjim]

Спасибо, коллеги!

[gni153]

Dear Messrs -тоже пойдет и еще как, если пишешь в компанию

[trtrtr]

http://english.stackexchange.com/questions/3700/how-do-you-greet-multiple-recipients-in-an-e-mail
http://www.englishforums.com/English/DearAllInBusinessEmail/zkqrq/post.htm

[Serge1985]

пишите "Hi, dear friend", например:

Hi, dear friend,
I am Mrs. Sese-seko widow of late President Mobutu Sese-seko of Zaire, now known as Democratic Republic of Congo (DRC). I am moved to write you this letter. This was in confidence considering my present circumstance and situation. I escaped along with my husband and two of our sons Alfred and Basher out of Democratic Republic of Congo (DRC) to Abidjan, Cote d’ivoire where my family and I settled, while we later moved to settled in Morroco where my husband later died of cancer disease.
I have deposited the sum Eighteen Million United State Dollars (US$18,000,000,00.) With a security company for safe keeping. What I want you to do is to indicate your interest that you can assist us in receiving the money on our behalf, so that I can introduce you to my son (Alfred) who has the out modalities for the claim of the said funds. I want you to assist in investing this money, but I will not want my identity revealed. I will also want to acquire real/landed properties and stock in multi-national companies and to engage in other safe and non-speculative investments as advise by your good self.
Yours sincerely,
Mrs. Mariam M. Seseseko.

[toast2]

dear sir, madam,
...
...
...

yours faithfully

забудьте "dear messrs"

[D-50]

When 'Yours faithfully' and when 'Yours sincerely' in a business letter?

When the recipient's name is unknown to you:

Dear Sir ... Yours faithfully

Dear Madam ... Yours faithfully

Dear Sir or Madam ... Yours faithfully

When you know the recipient's name:

Dear Mr Hanson ... Yours sincerely

Dear Mrs Hanson ... Yours sincerely

Dear Miss Hanson ... Yours sincerely

Dear Ms Hanson ... Yours sincerely

When addressing a good friend or colleague:

Dear Jack ... Best wishes/Best regards

Addressing whole departments:

Dear Sirs ... Yours faithfully