Sir or Madam' is a respectful way to address the person when you don't know their gender
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Example
Dear Sir or Madam
...
Kind regards
Susan
Sir or Madam' is a respectful way to address the person when you don't know their gender
Sir or Madamは、相手の性別が不明なときに使う丁重な宛名です。
_________________________________
Example
Dear Sir or Madam
...
Kind regards
≪例≫
Dear Sir or Madam
Kind regards,
Susan
If you are sending and email to someone you are not aware of their gender it is better not to make any assumptions because they may be offended if you are wrong. There if you address the email with the above you do not have to include the gender when addressing them.
To whom it may concern - an expression written at the beginning of a formal letter when you do not know the name of the person you want to communicate with
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You can say "To whom it may concern" if you don't know the persons gender.
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gender - male/female
To whom it may concern - 連絡したい人の名前がわからない場合に正式な手紙の冒頭に書かれる表現
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相手の性別がわからない場合、"To whom it may concern"と言うことができます。
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gender（性別） - 男女
Many parents are opting to give their baby girls traditional boy's names. For example, Blake Lively, whose own moniker isn't classically "female," has named her newborn daughter James. In fact, it's a tactic that has long had a place in Hollywood. Drew Barrymore, Reese Witherspoon, Hayden Panettiere, Parker Posey, Taylor Swift, Cameron Diaz . . . they all borrowed these names from the boys.
So how do you know if you are replying to a male or a female if you have never met them? Well, there is no way of knowing, so you can only respond to them using either the full name or just the first name.
You have to reply to an e-mail and you have to address the person as either male or female. However, you do not know the gender of that person. You may take a chance and address the person as Mr/Ms. You already know, of course, that the person is ,either male or female. So, addressing that person as Mr/Ms is appropriate because, upon receiving the e-mail, the addressee will identify himself/herself with either Mr, if he is male, or Ms if she is female. Also, addressing the recipient as 'to whom it may concern' rules out any gender issues. However, this does not sound appropriate as an e-mail address.
So, you may address the person as follows:
Dear Mr/Ms
or
Dear Sir/Madam (most appropriate)
or
To whom it may concern. (appropriate for letters or testimonials)
Eメールの返事をしなければならない時、男性であれ女性であれ宛先を書かなければならないですよね。でもその人の性別が分からない。そんな時は、Mr/Ms.と書けば大丈夫です。当然人は男性か女性のどちらかだから。だから、Mr/Ms.と書くのはふさわしい対処法だといえるでしょう。なぜなら、相手が男性ならMr.、女性であればMs.とすることができるからです。
また、"to whom it may concern"という言い方は性別を気にせずに使うことが出来ます。しかし、これはEメールの宛先としては不自然です。
よって、以下のように言うことが出来ます。
Dear Mr/Ms
Dear Sir/Madam (一番自然です。)
To whom it may concern. (手紙や感謝状を書くときに使うといいでしょう。)
If you are replying to an email and you don't know if the person you are emailing is male or female, you would say any of the following: "Sir/Madame", "Mr/Ms" or "To whom it may concern"..
Example sentence: Dear Sir/Madame, I am responding to your email.
性別の分からない人にメールを書くときは、次の表現が使えます。
"Sir/Madame" "Mr/Ms" "To whom it may concern"
例文：
Dear Sir/Madame, I am responding to your email.（いただいたメールのお返事をお送りしています）
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