Almost everyone has received the bogus emails from banks, eBay, paypal, mortgage companies, other finance companies and so on known as phishing. These scams are very clever, seductive and they look almost identical to the "real thing". Smart people get fooled every day. These scams are run by thieves who hope to get your personal information so that they can use it to steal.
These new scam emails claim to be from the IRS. It states that someone else is using your credit card or bank account in a fraudulent way or to pay taxes and that your funds are now "blocked" or "frozen" to protect you. You now must click on a link and provide personal information (passwords, social security numbers, etc.) to get your money "unblocked". The email and the link are similar to the format used by the IRS, but the IRS as well as any legitimate company would NEVER ask for personal information this way.
I have received "phishing" emails which look exactly like emails I get from my bank. They can be very hard to detect. If you have business with your bank, either type their url into your browser and contact them that way, or call them or go to the bank. Be very wary about putting your personal information--passwords, date of birth, social security number, account numbers, and the like anywhere online. In fact, make it a "rule" not to do so, and make sure your children (and your parents, the elderly are common targets for fraud) understand and follow this rule.
I have also received phishing emails from companies that I do not have accounts with. These crooks threaten some pretty scary stuff in their follow-up emails when you don't respond. They will close your account, charge you fees, blah, blah, blah. These are pretty easy to recognize. If you don't have an account at Bank Z, they can hardly do anything to you.
It's when you do have an account somewhere that it's scary.
In those cases, I suggest reporting them to the actual company they claim to be from. Again, Do Not click on any links in the email. Go to the company's website (type their url into your browser), check out "contact us" and then see if there is a "phishing" email address. If so, forward the bogus email to them. If you are not comfortable with this, just delete the email.
Phishing crooks are also targeting internet users in other ways, such as dating sites or social network sites (like Myspace). Those sites ask for quite a bit of personal information when setting up your account. Instant messaging and telephone messaging are also used to fraudelently obtain iformation, so one can never be too careful.
Once an identity thief has some of your personal information, it can be used to get other information. In the very recent past, one's social security number was often printed on your personal checks, your driver's license and used as an ID number at places of employment. With just that, a crook can open a charge account and much more in a very short period of time. So, protect your personal identifying information, especially online, and be aware of the ever-evolving ways crooks can trick you out of your money.
For more detailed information about phishing, you can buy Phishing Exposed from Amazon.com.