I do not know if this is true, but it is what I have heard.
Firefox preferences -> security -> block dangerous and ... If this setting is
marked, any url you watch is send to google, because google verifies with
their url list. Google likely keeps the data. I do not know if google pays
mozilla for the data.
Now it is said that several, like android apps, firefox addons transfers data
about the user to google or another entity. The data may get sold and who
knows how it is used.
What about firefox and thunderbird addons? Can't they hidden for the user
transfer data and the user will not know to whom or what data? Is there a
addon whitelist that lists addons that do not spy on you?
