Epis: I wrote it once, I’ll write it once again. Shlomis bas Divrie also did it. She greeted people of both genders at all occasions, as Chazal tell us. “Shalom alach, Shalom alach”. Much to her undoing. She too did not see anything wrong – being friendly, cordial, social, “proper etiquette”, “gemutlach”. That was her inner flaw that brought her to no good…. Chazal suggest otherwise.
We follow Chazal who tell us not to, ??? ?????? ????? ???, and many other sayings.. ????? ???? ?”?…
So in a place where it’s the norm, it’s not flirting (I’d maybe think there can be a difference between a woman engaging and a man – maybe a woman engaging is too pritzus – like Shlomis did, again, just maybe), otherwise it should not be done.