From MozillaZine Knowledge Base
Firefox 2.0 incorporates the Google Safe Browsing extension in its own Phishing Protection feature to detect and warn users of phishy web sites. This preference switches between using a local blacklist to determine a site’s phishiness, or submitting the URL to a third party.
The latter option (“enhanced mode”) was removed with the update to the Safe Browsing protocol, and this preference has no effect in Firefox 3.
Possible values and their effects
Consult a third-party provider to determine whether a site is phishy.
Compare visited URLs against a blacklist to determine whether a site is phishy. (Default)
Mozilla Firefox 2
Radio buttons labeled “Check using a downloaded list of suspected sites” and “Check by asking _____ about each site I visit” are located under “Tools → Options → Security / Tell me...”
First checked in
Has an effect in