The lowest tech solution is to use your delete key. If you're lucky enough to only get a handful of unwanted messages a day, this works. But you run the risk of deleting an important message along with the junk. So once you join the real world and start getting tens, hundreds or even thousands of spam emails a day, you need a stronger solution.

The next laziest solution is to rely on your email service provider to categorize messages for you. Services such as AOL and Hotmail do this with varying degrees of success. Some email service providers use a system called BrightMail. The biggest problem with these methods is that you often don't actually know what is being let through and what is being blocked. There's just a digital dustbin somewhere where all the messages that are deemed to be spam get sent and humanely destroyed. This works OK most of the time but can be a real pain in the neck at other times. The problem is that spammers don't care whose email address they hijack. They don't send emails out with a real return address (they're not that stupid!). Instead, they randomly choose an address to pretend the email was sent from. So if your granny's address got used to send out a few thousand messages she could just as easily end up on a blacklist. Then you'd never get messages from her and you'd have no idea why.

Some people turn to services like Spam Arrest. These offer a "challenge response" system that is supposed to block spammers. The idea is that the first time you get an email from someone, they get sent a message asking them to confirm they are human. You get their original message but only once they've clicked on the link in the email they get sent. The theory is good. The practice is less good. Many people hate these services to such an extent that they don't click the return link - especially if they've read the terms and conditions associated with clicking it whereby you sign away your soul or something like that. So you then have to manually "approve" the people who refuse to click on the return links. Which is almost like going back to square one.

The best services are ones where you have complete control. You need to spend a little bit of time teaching them what email you want to receive and what is rubbish. But once you've done that (it only takes a handful of minutes) they'll work with you to filter your email and keep you almost 100% free from spammers. If a spam message does manage to slip through, you mark it as such and the system learns for the next time.