I understand that for men you use either Mr. Surname or Surname-san when addressing them (but never Mr. Surname-san) in formal business communications, but I am not sure of the proper way to address a business woman. The only thing I’m certain is that Mr would be incorrect.
To my knowledge, there is nothing corresponding to “Mr.” in Japanese other than the suffix “san.” Also, “san” is gender neutral. So surname-san is the way to address someone in business situations (and many other situations) whether you are addressing a male or a female.
-FrL-
Thanks, I was confused because I saw only one email in the last 5 years refer to a woman who was actually in Japan and they were throwing around a -sa on the end of her surname. Most of the Japanese women I deal with are here in the states and they tend to allow the Americans to drop the formalities.
-san is gender-neutral, so both Mr. Suzuki and Ms. Suzuki would be addressed as Suzuki-san.
eta: -san is also independent of marital status, so Miss Suzuki and Mrs. Suzuki would also both be addressed as Suzuki-san. Convenient!