The type of salutation appropriate for a business letter depends on whether you know the name and gender of the recipient and the type of relationship you have with the recipient. Start with "Dear" followed by the recipient’s personal title and full name, if you know both. If you do not know the recipient’s full name, use "Mr.," "Miss," "Mrs.," or "Ms." and the last name. "Ms." is the preferred choice if you are unsure which salutation a women prefers.
Follow the salutation with a colon if you are writing a formal business letter. If you are writing an informal letter, address the person by his first name and follow it with a comma: for example, "Dear John," versus "Dear Mr. John Smith:." If you are unsure of the recipient's gender, use the full name and leave out the personal title, for example, "Dear Adrian Smith.”
If you don't know the name of the recipient, use a job title, such as, "Dear Marketing Manager" or "Dear Human Resources Director." If you do not have a specific person in mind, use a standard greeting, such as “Dear Sir or Madam," but avoid the generic greeting "To whom it may concern." It is also acceptable to use the name of the company in the salutation, for example, "Dear XYZ, Inc."