Equivalent to Ms?

Question

Is there a Spanish equivalent the the English "Ms." as in "Dear Ms. Smith,"

If there is not an equivalent, which is preferred between Señora and Señorita when you don't know the marital status of a woman or she prefers not to have her status indicated by her prefix'

Answer 1

Lazarus, I hate to ever disagree with you because you are right so much more frequently than I am. But, Señora is Mrs.

Answer 2

Ms = Sra. (señora)
Miss = Srta. (señorita)

Answer 3

Señorita is the equivalent to Miss. I have seen it before, I think that it is Srta, but I may be mistaken. I know that Señora is Sra.