Q: How long do people in the US say “Happy New Year”?
A: There is no “set date”, so it really depends on the person and the situation. Usually, we only say it in person on New Year’s Eve/Day and maybe for a few days after.
As you know, we don’t have any kind of long break for the New Year’s holiday – just New Year’s Day
off work. So it’s common for people to include the greeting in emails that are sent out when they return to work on the 2nd.
As to why you are still receiving this greeting, my guess is that it is because the people you are corresponding with are aware that for Japanese people, New Year’s Eve and Day are important holidays, time to be spent with family, and time that is rich with tradition. They are likely extending this greeting to you because they want to make a point of recognizing a day that is important in Japanese culture.
（和訳）
Q: アメリカ人はいつまで”Happy New Year”を言うの？
A: 決まった日にちはないので、その人と状況次第ね。対面で言うは、大晦日と元日、そのあと数日間だけよ。ご存知の通り、私たちはお正月休みは長くないのね。元日が休みなだけなの。だから２日に仕事に戻ってメールを送るときに”Happy New Year”のあいさつを入れるのは一般的なことよ。
あなたが今でも”Happy New Year”の挨拶を受けることについては、あなたがやりとりをしている人たちが大晦日や元日が日本人にとって、とても大切な祝日で、家族と過ごし、習わしがたくさんある時間であることを知っているからね。日本文化で重要な日だと認識をしてることを表したくてこの挨拶をする傾向にあると思うわ。
