If you check the IRS web page you will see a disclaimer that no one in the agency will send you an e-mail. Sorry, they aren't that friendly.
Do not click on the link in the e-mail. We suggest that you send it complete with headers (the return address path that you might find by clicking on "View Full Header;" you need to copy and paste that information to the top of the message you are forwarding, if it isn't already apparent.) here.