There are four stages to a situation, unaware, aware, alarm and alert. Just as if you are walking alone in a parking ramp at night, you always need to be aware of your surroundings when on the internet. A common e-mail scam is known as “phishing” this is when you receive an e-mail with an official logo from a bank, credit card company or the IRS asking you to log in to a website to confirm a charge or information.
First, the IRS never sends these e-mails and the other’s most likely will not send them either. Second, review the web address, it will be almost obvious not the same address you normally log in to. They set it up to look like a log in page, collect your username and password to actually get into your account. Ignore these links and contact the actual company (not from any info on the e-mail) to verify if any real information is needed.
Inherited funds/Lotteries/Cash Consignment e-mails are always scams and other e-mails or letters asking to fill out forms and send to the IRS are usually forms you file with companies or financial institutions like W9’s or W-8BEN.
Lastly, I have noticed that e-mails originating outside the US have grammar or phrasing problems as English is not their first language.
Link to IRS information page on scams.