People can hem and haw about the specs, but at the end of the day Gmail trained most of the world to believe email addresses are case-insensitive, dots don't matter, etc., and now we have to live with the consequences. If that means somebody can't sign up for twelve accounts using case and dot variations of their Gmail, well, so be it. And if that means they come to HN to rant about how that awful site didn't follow the RFCs, then they come to HN to rant about that, but their account will be safer in spite of it.