That depends on what you know about the person. If they are unmarried, you can use Miss. If you don't know, or don't want to impose the status, you would use Ms.
Ms.
You use ms when writing a document, e.g letter.
miss or ms.
By their first names, if it's informal. Otherwise Dear Mr ...... and Mrs/Miss/Ms .........
The proper way to address a female boss in writing is to use Dear Miss and then the name. If she is married then use Ms. or Mrs. instead.
miss.
Mrs. is when a women is married. Ms. is when they are not married. Miss is when thay are younger.
American people use the title Ms. to address women, over 18 that are either married or unmarried. Women who are under 18 are addressed as Miss.
You can use Mrs., Miss, or Ms., depending on the marital status and preference of the woman.
You would write his/her name on the envelope as: James Smith, NP Jane Doe, NP You would use Mr. Smith or Ms. Doe in the body of the letter; "Dear Mr. Smith," or "Dear Ms. Doe," (you would use "Ms." in the event you are not certain if they are a Miss or Mrs.).
You can address an unmarried woman as "Ms." just as well as a married woman. In a situation where you are unsure of the marital status, "Ms." is a safe form of address, and avoid "Miss" and "Mrs."
The standard two letter abbreviation for the state of Mississippi is MS.