Rule number one in e-mail safety is never open suspicious messages.

But even after hearing that over and over again, we computer users do click without using our better judgement. And sometimes we even take the bait.

Prime example: Thomas Katona, a former long-standing treasurer of Alcona County in Michigan, USA was arrested after he allegedly invested over $1.2 million of the countys funds in an e-mail scam. Katona was found to have transferred both personal and county funds to overseas accounts that had been linked with Nigerian 419 scams.

E-mail scams these days are surfacing in all different shapes and sizes.

The evolution of the "storm worm" is another example of why we always have to be cautious. Instead of using breaking news headlines to spread infected messages, last weeks Trojan e-mail attack has changed tactics to use messages of love, researchers are warning. The scam is now reportedly using subject lines that mimic greeting cards, like "Dream Date Coupon," "5 Reasons I Love You" and "You're So Far Away." The messages are sent with malicious file attachments named "flash postcard.exe" or "greetingcard.exe."

So, even though you've heard it before - many times over - we just can't resist. Think before you click!