Google is number three in a list of web service providers responsible for spam, says Spamhaus.

Junkmail watchdog Spamhaus moved the search engine up one place from fourth to third in its list of spammy ISPs and web-service providers this week. According to Richard Cox, Spamhaus' CIO, while free Gmail accounts are often used to send spam, it's the way spammers are manipulating Google Docs, that causes more of a problem.

Cox said a feature in the application that allows users to share a document that is assigned a URL is being exploited. These documents contain a 'redirect' command, which can be used to push web users to spammer websites, which often sell pharmaceuticals

Spamhaus has had trouble getting top-level attention from Google about the problem, Cox said. That's in contrast to Microsoft, which took steps recently to stop spammers from putting redirects on free web pages and sending out the links as spam.

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A top Microsoft executive finally took note of the problem after being alerted by Spamhaus, Cox said. Microsoft hasn't detailed how it is stopping the nuisance, but its method appears to be working, Cox said. Spamhaus has had less luck so far with Google, he said.

When contacted, Google did acknowledge the problem.

"Spam is an issue for all internet users, and we actively work to disable accounts that are found to be in violation of our product policies," Google said. "We're aware of this Google Docs spam issue, and we've already begun implementing improvements to minimise the impact of the issue."

There are a couple of fixes. One would be to simply halt the use of redirects, Cox said.

"We don't see why when Google and Microsoft hand out free web pages to people they should then allow those people to put a redirect to another site. The only people using redirects are the spammers."

Another method would be to check the URL to which a redirector points. If it is listed on Spamhaus' Block List (SBL) of verified spam operations, the message could be blocked, Cox said.

Services such as Tiny URL, which make long URLs shorter, block those URLs that redirect to sites on the SBL and thus don't have the problem, Cox said.

See also: Can Google Apps beat Microsoft Office?