More than once on this site, people have offered workarounds, such as http://www.bugmenot.com, why not use them? Or get a throw-away email address specfically for such online use? Asking for an email first is a simple device that helps reduce the rate of bogus or automated participants. There are so many practical steps that can be taken to accoommodate this perfectly reasonable request, without resorting to plaintive hand-wringing.