This is taught to children in the United States. I didn't go to an especially good school and I remember it to this day. If you're not from the US the custom may be different.
Perhaps you will consider the advice from Grammarly [0] as a more acceptable source.
[0] https://www.grammarly.com/blog/commonly-confused-words/ms-mr...
No doubt, in today's absurdly woke school system.
there is woman,
and there is Klinefelter's.
(worth the karma hit)
Miss indicated that a woman was unmarried. Mrs indicated that she was. Ms was added to behave like Mr in that it doesn't indicate marital status.
Especially in a business context, it would be unprofessional to ask if a woman is married or not merely for determining which title to use. Unless you want to have an affair with her, of course.
Hm. Weird. Never seen that before. Let's check the source, emilypost.com:
>Mx. Is the universal title that can be used by anyone. It is gender non-identifying. Even if you identify specifically with a gender you may still use Mx. and you may see Mx. used when the sender is unaware of your title.
https://emilypost.com/advice/guide-to-addressing-corresponde...
OK, im out. I'm immediately out.