membership fishing scam emails

Hey, I don't know about the rest of you guys, but we have been bombarded with member account fishing emails recently. Its been going on for about 2 months now. People write things like:
"I can't remember my login but it was roger or steven or something like that"
or
"I joined about a week ago before your site was up. Did my membership become active?"
etc....

It seems people are fishing for free memberships. None of these emails have memberships either, when I write to ask them what site they joined and what email they used when signing up, I never hear back.

I received the same emails