We've all had this experience: You login to your email account, excited to read messages from friends, relatives, co-workers, or your girlfriend perhaps. You view the link to your inbox, and it says you have five messages. Fervently, you open your inbox, your heart is racing, you sit up in your chair a bit, leaning forward closer to the computer as you get ready to enter a new dimension.

What do you find when the page finishes loading? Well, you see a spectacular cornucopia of diverse, informative topics referenced in the "subject" for each email:

"Erectile Dysfunction? Look no further - Viagra, 90% off!"

"Get a 200 year mortgage!"

"Reverse the aging process, regress back to infancy!"

"Make 10 million dollars per hour stuffing envelopes!"

These emails can try a man's patience. It would be one thing if you had signed up for a service that emails to you, every 5 minutes, titillating offers that, if they were true, could make you the richest man in the world with a mortgage that your ancestors, 200 years from now, will pay off in full, unless the house has completely rotted to the ground by then. However, most of these emails come unsolicited. How the heck did they get your email address in the first place? Well, I'm not really sure.

Just kidding! There are a variety of tactics that spammers use to get your email address. Sometimes, you sign up for a service or buy a product from a website, and when you provide your email address during the order process, the individual who runs the website and is collecting the information then turns around and adds all of those email addresses to his electronic address book and sends you offers from an email address associated with a totally different domain name so you don't know it's him.

Sometimes, these clever marketers skulk around message boards and other internet forums and just copy all of the email addresses for each of the people who have posted messages to the board, and they can usually collect thousands of email addresses this way.

One way they can then build upon their treasure trove of stolen emails and grow their list exponentially is by then sending a joke to the various people on the list, something that they got off a website. The joke could be about George Bush. On the other hand, it could be a joke about someone who was born with a brain. When you decide to forward these witticisms to all of your friends and list all of their email addresses in the "To" or "Cc" fields, you could be actually sending all of your friends' email addresses to the spammer who sent you the joke. Clever spammers use programs that grab email addresses when you forward or reply to such a message.

Sometimes these email larcenists send you an email message with an exciting subject that causes you to open it, and then there's not much there, but by opening the email you've unleashed a Trojan horse that crawls out of the email and onto your hard drive and grabs email addresses that are stored in folders on your computer where you save your "Buddy List" if you use AOL, or strips the email addresses off of any and every email you have saved on your machine. The virus then proceeds to send all of these stolen email addresses back to the perpetrator, who may have just grabbed 100 email addresses off of you, maybe more.

Finally, what happens a great deal of the time is people who are successful at building email lists, sometimes with a legitimate business where they have a huge database of 10 million or more email addresses, turn around and sell that same list over, and over, and over again to the spammers. This happens all of the time, and there's really no way to stop it. Your email address has probably been sold a thousand times since you started using email, you just don't realize it.

So, how do you prevent spam? Well, you can use message filters that filter out emails that contain certain keywords (most email accounts come with a filter), you can block certain email addresses, or you can set up a very sophisticated set of "message rules" if you have email client software that has this option, and with this feature you can really set some very specific boundaries for your email account.

So, be aware of all these techniques that spammers employ, establish some ground rules for your email account, and you can probably avoid most spam in the future.