Spam filtering review and compare

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Test results for seven popular free spam filters and four email clients with built-in spam filtering capabilities

Anyone using email these days will eventually encounter spam — junk email that can clog up your inbox. Spam is not only annoying, but also potentially dangerous. Its often used for spreading malicious software such as viruses, adware or spyware, or even leading to the theft of your personal and financial information.

The good news is that a good anti-spam program is as far away as a free download. Spam filters are the guardians of your email inbox, identifying and diverting spam emails automatically, weeding out the ‘suspect’ from the ‘safe’ (also known as ham).

If you’re using Windows XP and Outlook Express, which doesn’t have sophisticated spam filtering built-in, you should consider a good add-on spam filter. If you don’t need to use a particular email client such as Outlook Express, you can use a free email program (client) that has spam filtering built-in.

Please note: this information was current as of March 2009 but is still a useful guide to today's market.

How spam filters work

Aside from an email client with built-in spam filtering there are three types of add-on anti-spam program:

Plug-in — operates within the email client to process spam as it is received. Plug-ins are easy to use because you don’t have to switch between email client and a separate filter.

Pre-step — a pre-step program is a program you run before you use your email client. It interacts only with the mail server, identifying and removing spam before you fetch mail in your chosen email client. Since it doesn’t interact with an email client like a plug-in, a pre-step program is compatible with all clients.

Proxy — a proxy sits between the email client and the mail server. All email passes from the email server to the filter proxy (where it is deleted or categorised) then to the email client. Proxies, like pre-step programs, should also be compatible with all email clients.

Spam filters tested

Add-ons for Windows

  • Bullguard Spamfilter 8
  • MailWasher Free 6.3
  • Popfile 1.0.1
  • SpamBayes 1.0.4
  • SPAMfighter Standard 6.4.23
  • Spamihilator
  • SpamPal 1.594

Full version free email clients

  • Windows Mail 6.0.6000.16386 (Windows Vista default email client).
  • Mac Mail 3.5 (OS X 10.5 default email client).
  • Evolution (Ubuntu Linux default email client).
  • Thunderbird (Third-party email client for Linux, Windows and Mac OS X)

We also tested four additional free spam filters but couldn’t get them to work satisfactorily and so dropped them from this test. They were: Sinapsi Antispam,SpamAware, SpamExperts Desktop Limited and xTerminator.

How you get spam

Even if you are careful about who you email and respond to, chances are your email address will still eventually be targeted by spam. Spam emails pop up in your inbox because spammers can get hold of your email address once it’s been exposed publicly on the net. Any email address you use has to ‘travel’ across the internet and it can be captured and used to send you spam. Email addresses are ‘harvested’ from chat rooms, websites, newsgroups and other online places.

They can also be collected by viruses that get onto PCs and copy users’ address books. Or they may even be ‘guessed’ by automated software. So, even if you do everything right, your address can still be captured from the contact list of someone you’ve emailed and sold on to spammers. So, you can’t stop spam, but you can stop it from being a nuisance by using an effective anti-spam program. Not all anti-spam programs work with all email programs so it’s important to check that the one you select will work with your operating system and email client.



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