In Japan, it's common to place "-san" after the email recipient's name, which is just another way of referring to the individual politely in Japanese, like Mr./Ms. If you are emailing a customer, the "-san" changes to "-sama", which is considered more polite.
But outside Japan, this "-san" applies mostly when you are emailing Japanese. I thought it was interesting to note that depending on the country and corporate, you don't have to necessary add "-san" in emails.
In US, from my experience, "-san" is added to the first name and not the last. If a Taro Suzuki sends email to John in the states, he will write "Hi John-san" and most possibly gets a reply back with "Hi Taro-san" (or just Taro).
In Europe, I mostly experienced "-san" added to the last name.
In APAC, same as in Europe, "-san" was added to last name quite often. If a Taro Suzuki sends email to Chang in Singapore, he will write "Dear Chang-san" and in return will receive response saying "Hello Suzuki-san". A lot of times, I got request saying they want to be called by their middle name since there are lots of similar last names.
In Japan, if you are a Japanese emailing Japanese co-workers, it's a must to add "-san" on the last name otherwise you are considered either rude or lacking common sense. But what if a Japanese contacts another Japanese working outside the country and when non-Japanese speakers are on the CC list?
Since the conversation must take place in English in order to share the information, I emailed my manager in English without "-san". It turned out to be a surprise for me that he did not say a word about me not adding "-san" but maybe he didn't like it. If the language was in Japanese, there would have been consequences.
If it's a Japanese company worldwide, most probably non-Japanese speakers will add "-san" for Japanese.
If it's a non-domestic company with an office in Japan, possibly non-Japanese speaker may not add "-san" for Japanese.
Depending on which country the head quarter is located in and its market size, the proportion of how many "-san" may differ.
I've asked several of my colleagues for the reason of using "-san" They were kind enough to come up with the following feedback:
Thanks to those who replied. Well, the most feedback I got was: Why do Japanese take the extra time to add "-san"? I totally agree but I wasn't much aware of it until now.
So, why not remove "-san"? I've started removing "-san" when I emailed my colleagues abroad and guess what? They started removing "-san" from my name as well. I thought it was really nice of them that they spend the extra time to add "-san" for every emails they wrote to me.
I guess using Dear Sir/Madam (or Mr./Ms.) on their last name will be polite enough. I once had a chance to send my resume and cover letter to the HR head who I have never met or spoken with. The above way is how I sent her the email. However if the conversation continues and if I persist to place Sir/Madam on each email, usually I get a response saying to quit using it and call me by my first name.
I figure people don't deal often with Sir/Madam.
Now, I try my best not to add "-san" as much as possible in order to avoid giving the recipients the impression that I may be forcing them for a reply back with "-san". Well, you might think who cares…
Depending on the country or the company you work for, the impression people have for "-san" may differ so it's probably up to you to decide where to use "-san".