I got a really odd email

It was titled ":)"
Body:
"U r awesome and the best twin sister a girl can ask for!! thanx for being there when I need u!"


I replied with:
"I think you might have the wrong email address.
Although it was a touching email and you sound like an awesome sister."

If anything I was expecting an embarrassed reply but I got something that totally stopped me in my tracks.

"sure look who r u lady"

I don't know how to respond if at all. I am so confused. Who talks like that?