There are no hard and fast rules about what greetings (salutations) to use in email. If you want to be polite and formal in English, then you should say something like:
Dear Mr. Smith:
Dear Ms. Jones:
Dear Dr. Jekyll:
Dear Prof. Einstein:
If you want to be polite and informal, replace the colon (:) with a comma:
Dear Mr. Smith,
etc.
When authors send me a manuscript, regardless what salutation they use to address me, I always start off this way:
Hi, Dr Jiang,
Hi, Prof Jou,
(Almost all my clients are Taiwanese doctors and medical school professors).
When I write to my friends, I always start of the same way:
Hi, Tam,
Hi, Kathy,
This is just a stylistic choice, a personal preference.
For business letters other than my editing, however, I always use the polite formal style in the first examples.
There is no definitive answer to your question, just a recommendation that for serious and important business letters (anything not to a friend or a penpal, and anything not informal), that you use the polite formal or polite informal style. You can find lots of choices in handbooks about how to write letters in English. Be advised, however, that different brands of English prefer different styles. The one that's best is the one you feel most comfortable with and the one that you think works best for any particular letter.
The more formal and more polite your initial salutation, the more emotional distance you put between yourself and the person you're writing to.
For friends and otherwise informal emails, the same rule of thumb applies: The one that's best is the one you feel most comfortable with and the one that you think works best for any particular letter.
Everyone has a different idea about what's good.
It can be seen as a little old-fashioned, but more accurate would be to say it is formal to use "I am writing to". However, it is still common for business letters. It definitely gives a sense that the author and recipient do not have a close relationship.
We use indirection to create a polite distance in both written and spoken communication. The recipient of the letter knows that you wrote the letter at some time. There's no extra information in the words "I am writing", but those words show a polite distance.
Think of the following examples and sets of thoughts:
- "I am writing to let you know you have won the grand prize."
- ... he/she wrote the letter and sent it, which means they want to tell me this thing. They want to tell me this thing and they did tell me. I should believe this thing.
- "I want to let you know that you have won the grand prize."
- ... he/she wants to tell me this thing. They did tell me this thing. I should believe this thing.
- "You have won the grand prize."
- ... that's surprisingly direct!
Best Answer
"Dear Sir or Madam," is the standard form. When not addressing someone by name, end with "Yours faithfully," not "Yours sincerely,". However, it is not too difficult to find out the names of people that you are writing to and you should certainly do this if you are making a job application or if you are writing an important business letter.