Whenever older guys, mainly ones who haven't met me in person, only over the phone or email, want to be clever or friendly, they call me 'Carol'.
Don't call me Carol! My name is not Carol! It's Carolyn! I have never, and will never, called myself Carol. It's not my name! If it were, my mother would have named me Carol! I would introduce myself as Carol, I would sign emails as Carol, and damn it, I would go by Carol!
Rule of thumb for everyone out there on the internet (not that I think you need it, because clearly you're smart, but it should just be out in the ether): don't refer to someone by a name they haven't called themselves. You will only get yourself into trouble.
End of rant.