And you thought spam was an e-mail problem.

Spam, those unwanted messages hyping miracle drugs, cheap knockoffs and cut-rate loans, has become the bane of blogs. In fact, some experts believe spam is a bigger problem for blogs than it ever was for e-mail.

That spells trouble for companies that have made blogs part of their customer service or marketing programs. Now, not only do small businesses have to work to keep their blogs in the public eye, they've also got to work to keep spam from giving them a public black eye.

But by following some simple steps, companies can block spam from creeping onto their blogs in the first place.

Spam in blogs is often called comment spam because that's where it shows up, in the section of a blog set up for readers to post comments. Spammers use software programs to sniff out blogs and post advertisements or links directing traffic to the spammer's website.

Anti-spam software to the rescue

Matt Mullenweg knows spam. Mullenweg co-founded Automattic, the company that makes the popular WordPress blogging software and created Akismet, an anti-spam program that's built into blogs. Akismet is also available as a software add on to blogs hosted elsewhere, including other well-known free blogging sites such as Blogger and TypePad. Akismet is an adaptive filter. When comments are sent to a blog they pass through mathematical algorithms that determine if it's a legitimate or spam. If a comment gets through that's really spam and a blogger marks it as such, Akismet 'learns' from its mistakes, Mullenweg says.

According to Mullenweg, 90 percent of comments that pass through Akismet are spam. He estimates the software has blocked 5.5 billion pieces of spam since WordPress and other blogs started using it in 2005. Though software programs like Akismet block spam, they haven't stopped it. 'Spam on blogs and the Web is where spam on e-mail was 10 years ago,' Mullenweg says.

Akismet isn't the only anti-spam software out there. Companies can also use so-called CAPTCH programs, short for Completely Automated Public Turing test to tell Computers and Humans Apart. The popular programs, which can be seen on many websites and blogs, require someone to take a simple test to prove they're not a machine before they can leave a comment. In programs such as reCAPTCHA, the test is typing in a sequence of squiggly letters or numbers.

Other software that blocks spam includes Bad Behavior, which analyzes the method and software being used to deliver a comment to a site to determine whether it's spam, and, Spam Karma 2.3, which works on WordPress blogs.

Common sense solutions to block spam

Anti-spam software is a blog's first line of defense, but there are other tactics. Blog experts and IT professionals also recommend that companies:

  • Check comments before approving them. According to Mullenweg, some off-shore spammers pay programmers to post what look like genuine comments. The solution: use a blog's comment moderation feature to check out comments before the go live. Or authenticate people before allowing them to leave a comment by requiring them to sign up for a user name and password.
  • Turn off comments. Not all blogs need two-way communication. Digital Forest, a 14-year-old Seattle, Web hosting and server co-location business, uses a blog to keep customers apprised of the status of the company's servers. When customers e-mail or call the tech support line they're directed to check the blog for information on maintenance and system updates, says Chuck Goolsbee, a Digital Forest vice president. 'We train our customers to look there, so if there's a problem, people go there first,' Goolsbee says.
  • Disable pings and trackbacks. Pings and trackbacks were originally intended to notify Blogger A that Blogger B had written something about them. But spammers use them to plant links to their own Websites in order to up their click-through rates. If trackbacks are a problem, don't use them, Goolsbee says. 'When you design a system you have to take into account how it can be abused,' and the creators of blog software didn't, he says.