The companies expect the joint venture to eliminate illicit websites from Yahoo! search results. Yahoo! said it also will flag dodgy sites in an effort to advise users of reported problems.
"Warning: Unsolicited E-mails" and "Warning: Dangerous Downloads" are among the warning messages.
Firefox Add On, Site Advisor's main product, provides similar warnings. It is comparable to Haute Secure and has been downloaded 135 million times, according to McAfee.
The new feature for Yahoo! search users is optional, but the default setting is "on."