Ms is a proper way to address a woman when unaware of her marital status.
The modern title 'Ms' may be less than elegant, but it is usually the best option until you know the person's preferred form of address. It looks far more polite than using just the name.
When addressing an envelope to a recent widow, it is customary to write the person's name starting with the title "Mrs.". Just because a woman is a widow does not mean that a woman is not still married.
Use "señora" when addressing a married woman, and "señorita" when addressing an unmarried woman. This distinction shows respect for a person's marital status in the Spanish language.
I was always told that you never seperate a man's name. So, if you are addressing a card or envelope informally, and the couple is married, it should be addressed: Jane and John Doe
A respectful way of addressing a woman is to call her Ms. or Miss. This is polite even when you do not know if she is married.
Addressing an envelop to a woman with a boyfriend and young son: Just address the envelope to: Ms. Jane Doe & Mr. John Doe (if the young son is in their teens, but not necessary if they are a minor) & Mr. John Smith. So the envelope may read: Ms. Jane Doe & Mr. John Smith.
Mrs. is when a women is married. Ms. is when they are not married. Miss is when thay are younger.
If you do not know if the woman is single; married or widowed then you can use 'Ms.' If you know they are single then use 'Miss' or 'Ms.' and 'Mrs.' for married women or widowed women.
"Mrs" means the woman is (or has been) married. Ms" means either of the above but the woman prefers not to reveal which, or is used if you are addressing her in writing and don't know whether she is a "Mrs" or a "Miss".
ethnicity has nothing to do with it.
Mrs means that the woman is married hence her last name is her married name. Miss means that the woman is not married and the last name is her maiden name. Ms could mean that the woman is divorced but has kept the married last name, or that the woman is married and has kept her maiden name???? maybe??? not too sure on Ms
Señorita
If you are using "lady" meaning a person of feminine gender, you may use: Missus (Mrs.) used when addressing a married woman. Miss used when addressing an unmarried woman. Ms. used when addressing of indeterminate marital status. Mistress, is an antiquated term for a woman who runs her husband's (or sometimes father's) household - these days it has other meanings. Madame, is a word borrowed from the French and used when addressing a woman of indeterminate marital status - most frequently by someone of lesser station. Ma'am, is commonly used in the southern United States when addressing any woman. If the woman in question holds a doctorate she is addressed as Doctor Whomever A woman Judge is Your Honour. A woman Mayor or other personage of political title is referred to as The Honourable, whomever. A woman of the cloth is address as Story, Reverend, Sister, Reverend Mother, Rabbi, etc. A woman in any branch of the Armed Forces is addressed by her rank or simply Ma'am. If you are referring to a woman who is married to a Lord or gentleman then the term Lady is used, often with her husband's (and these days her own) titled lands. ie. Alice, Lady Belfor. There are related links below to further muddy the waters of etiquette.