http://www.irs.gov/privacy/article/0,,id=179820,00.html
Partial content of official irs link above regarding phishing and email scams:
What You Can Do to Report Phishing, E-mail Scams and Bogus IRS Web Sites
If you receive an unsolicited e-mail communication claiming to be from the IRS, please forward the original message to:
phishing@irs.gov using the instructions provided below. You may not receive an individual response to your e-mail because of the volume of reports we receive each day.
* The IRS does not initiate taxpayer communications through e-mail. In addition, the IRS does not request detailed personal information through e-mail or ask taxpayers for the PIN numbers, passwords or similar secret access information for their credit card, bank or other financial accounts.
* Do not open any attachments to questionable e-mails, which may contain malicious code that will infect your computer. Please be advised that the IRS does not initiate contact with taxpayers via e-mails.