One of the important lessons that we attempt to teach our students is to be proper digital citizens.
The major concept of this is online safety and information security. To this end we have recommended that the students set up a school gmail account separate to their personal emails.
They can do this very quickly. Most Web 2 tools require a email login and so for both ease of use and security we ask them to use this gmail account for nothing else. This means that at no time do commercial companies or third parties get hold of student's personal email information.
Of course we also have the conversation about not giving out any personal details at all and that if that situation comes up that the teacher is to be notified immediately.