Stop spam

Don’t get mad...
When you receive junk mail it’s tempting to send off a furious email to the sender. However, as ever with spam, all may not be what it seems. This is because spammers often hide their identity behind innocent people’s email accounts.

When sending an email it’s very simple to disguise the sender’s name, so spammers often pick an address from their list of targets and use that ­ if you and hundreds of others send an angry email, you’re simply inundating that innocent person with messages. In many cases, they won’t even know that the spam has been sent in their name. Some spam bots note when a victim responds, h ighlighting that address as ‘live’ and earmarking it even more ‘special offers’.

Instead of getting mad, the best policy is to set up mechanisms to remove spam before you even see it. There are three key ways to do this: blacklisting, whitelisting and intelligent filtering. We’ll explain what these are, and how to use them.

Blacklisting is the most common of the three. A blacklist holds a list of sender email addresses or text patterns that are known to have previously appeared in spam emails. When emails arrive that match any of the entries in the blacklist they are known to be spam, and are moved to a folder or deleted. You can create your own blacklist, but usually spam software relies on a blacklist that is stored centrally on the internet and regularly updated by the spam filter provider.

Although blacklists are very effective at cutting down on spam they don’t totally solve the problem. This is why some people choose to rely on whitelist filtering instead. Whitelisting is the opposite system to blacklisting: a whitelist contains the addresses of people you want to receive email from, and only emails from people on that list are allowed through.

Whitelisting is a brilliant way to cut out loads of spam, but it’s too limiting for many people. Most of us need to be able to receive emails from people we don’t know and whitelisting doesn’t allow for this. However, whitelists can be useful in certain circumstances. For example, if you want to give younger children an email address, a whitelist is a good way to control who they can and can’t receive email from.

Instead get even
More and more anti-spam filters are now using intelligent filtering using a technology that’s often called Bayesian or Heuristic filtering. These learn what to classify as spam based on previous experience. For example, if you get an email with the word ‘loan’ in it, the filter doesn’t automatically presume that this is spam. However, if the email also contains the phrases ‘bad credit’ and ‘apply now’ the filter might recognise that this combination indicates the message is most likely to be spam and filter it accordingly.

Intelligent filters judge a message’s header, ‘from’ address and main body text against thousands of such rules before giving it a score. Once a message scores above a certain threshold it is filtered as spam. You can usually adjust the filter’s sensitivity to raise and lower this threshold.

Most common email applications include some form of whitelist or blacklist filters. The filter built into Microsoft Outlook 2003 has a Blocked Senders List (blacklist) and a Safe Sender’s List (whitelist). To make use of these right-click on an email in your Inbox, highlight Junk E-Mail and select either Add Sender to Blocked Senders List or Add Sender To Safe Senders List.

If you choose the Blocked Senders list the email will be filtered to your Junk E-Mail folder and all incoming email from the sender’s email address will be blocked in the future. Outlook also includes Microsoft’s Smartscreen Technology ­ an intelligent anti-spam filter. You can adjust its filtering level by going to the Tools menu and choosing Options. From here select the Preferences tab and click on Junk E-mail. The window that appears lets you switch the filter between high or low sensitivity, turn it off completely or make it only accept email from senders in your Safe Senders list.