In one word -ignore.
The IRS does not, repeat does not, initiate contact with taxpayers by e-mail. So any e-mails you receive saying you have a refund due or wanting info, are bogus and you do not want to respond. It doesn't matter how authentic they look, they are still scams and they just want your banking info or to plant a bug in your system.
If you want to do something, you can report the e-mail at email@example.com. The IRS has a whole page of info on e-mail scams and phishing on their web site.