Buongiorno signor Verdoni come stai or come sta, which one is correct for this sentence?

"stai" is the conjugation for the second person singular informal [tu]. come stai? - you're talking to a friend, family, a child. "sta" is the conjugation for the third person singular and second person singular formal [lui, lei / Lei]. come sta? - you're talking to someone you've never met, your boss, older people, etc. lui sta con lei - you're talking about a third person, a "he" in this case.