That's an interesting idea, but as someone noted, most of the emails involved here come from a small set of domains, such as blogger or anonymous mailinator typ

That's an interesting idea, but as someone noted, most of the emails involved here come from a small set of domains, such as blogger or anonymous mailinator type emails (emails which are possibly crawled by google often!) I think if it were google's toolbars picking up urls in emails, that there would be many more email domains here.