Google Custom Search Engines (CSEs)add much power to Google search. Based on Schema.org object definitions, sites can “tell” Googlebot that they have objects, like a Person object. The definition of a Person has tons of fields, but sites usually implement only some. CSEs can pull sites with “Persons” and narrow down to the presence of some fields or their values.
What is interesting is sties that have the Person object with an Email field. To find sites that do support it, you can use a Find Everything CSE, which searches across the web with no restrictions. The operator to