Aks HN: Looking for a niche which make intensive use of emails

Hi, we are developing a product which will give users infinite email addresses. The product at the moment is only an idea and a landing page and we are trying to figure out a particular niche that could be interested in our product. The idea is to let people create a usable email address whenever they want, they will be able to block any email they create and don't receive any more annoying email. Do you know any particular niche that make intensive use of email and would benefit from the product ? Of course, if anybody is interested please send me a PM and I will sign you up for the beta.