Salutations for letters can be confusing depending upon who you are addressing and the level of familiarity with the recipient. Proper letter writing is an art form that has fallen out of favour for some. However, knowing how to properly use various salutations for letters can make any letter seem more professional or elegant and thus impress your recipient with your knowledge of letter writing etiquette.
Professional letters deserve a certain amount of formality when utilising various salutations. Job inquiries and cover letters should utilise "Dear, Mr. or Mrs" if you know the name of the person you are addressing. If you are unsure of the name of the person the inquiry or letter will be going to, you may state "Dear Human Resources" or "Dear Sir or Madam," or the more gender neutral salutation, "To whom it may concern." If you know the title of the person you are addressing, you may also utilise the title in the salutation, such as, "Dear Director of Marketing" or "Dear Pastor Jones."
Personal letters can take on a less formal tone, however the level of familiarity with the person you are writing to will bear on the proper salutation for the letter. For close friends and relatives you may simply state the individual's name or say "Hi John," instead of "Dear." However, for acquaintances you may wish to state the person's first and last name, such as "Dear Tom Jones," or if you are relatively unfamiliar with the person you are writing it is best to err on the side of safety and utilise an honorific such as "Mr." or "Ms."
Letters of High Position
When addressing people in high positions, such as nobility, government officials or religious figures, the letter-writer should always be cognizant of the culture of the person to whom he is addressing the letter. In American culture, for those in government positions, one should check the title of the person and address the letter accordingly; for example, judges should be addressed as "The Honorable" whereas in British culture one should address high government officials as "Your Excellency." It is of vital importance to do your research on the rank and position of the person you are addressing so as to not offend or disrespect the office of the letter recipient.
Groups and Couples
When addressing a group or a couple, you can utilise a variety of different salutations. The most common salutation for a pairing is "Dear Mr. and Mrs.," or if in a public office or position one would utilise the title of the person holding the title such as Congressman and Mr. Smith. When addressing a larger group of people one may wish to say "Dear Friends" or "Dear Colleagues" depending upon your relationship to the people you are addressing. For couples not married, you should simply utilise each person's honorific and his or her surname, for example, "Dear Mr. Smith and Ms. Jones."