Wrte.io is a beta service that aims to make your emails profitable. The service charges 0.99 per email, with senders being billed before their email is delivered. Payment is processed via debit/credit card or Bitcoin with a small fee assessed. You can choose to either collect the fee or donate it to charity. The service doesn't seem to be for everyone, as it's highly unlikey that personal contacts would pay to email one another.
That being said, Wrte.io does seem especially useful for those in marketing or those who receive random emails all the time, such as venture capitalists. It really does show dedication if someone is willing to pay to send an email, and if the idea is trash a wealthy VC can always donate the money to charity.