Thunderbird users can also customise how junk e-mail is received and dealt with. If the Junk filter is enabled (go to the Tools menu, then Account Settings, then Junk Settings, then 'Enable adaptive junkmail controls for this account'), all suspicious e-mail will carry a green junk icon, leaving you the choice of deleting it, or clicking the button 'This is not Junk'. In the case of the latter, future e-mails from that sender won't be treated as spam. Within the Junk Settings menu there are further options to move new spam to a Junk folder (recommended) automatically and to delete junk mail older than a specifiable amount of time. To prevent trusted e-mails being marked as junk, there's also the option to 'Not mark mail as Junk if the sender is in your personal address book'.

It's also possible to train Thunderbird to identify what's spam and what's not. To do this effectively, you'll need to mark all mail as either Junk or Not Junk by right¬clicking the message and selecting the corresponding option from the list. The associated keyboard shortcuts are J for Junk and Shift and J for Non Junk. And the more you teach Thunderbird, the more Junk will automatically find its way into the Junk folder. Don't forget to check the Junk folder occasionally to ensure it's doing its job properly.

Outlook Express can also be trained, but in a different way, using Message filtering. Rather than simply blocking a sender, as discussed earlier, you can instruct Outlook to deal with certain e-mail in a certain way. Within the Tools menu, click Message Rules, then Mail. Create a new 'rule' for the program to follow by clicking the New button and selecting certain conditions and actions. For example, you could select the following Condition: 'Where the Subject line contains specific words -loan, Nigeria, increase' and the following Action: 'Move it to the specified folder Junk'.

But there's no need to settle for the spam filters built in to e-mail applications such as Thunderbird and Outlook. Most of the main Internet security suites, such as AVG Internet Security, Norton Internet Security, McAfee Internet Security Suite, Panda Internet Security and even Tesco's budget Internet Security suite, include anti-spam tools. Some ISPs also offer a spam filter, either run by the ISP itself or using elements of the packages offered by the big names in PC security. These check incoming mail for spam and separate these messages from legitimate mail before they even get to your inbox. You'll often have to pay extra for anti-spam tools. Contact your ISP for details of the protection it offers.