I really don't understand the point that 'the charity loses out' by emailing quizzes. The charity saves the cost of printing quizzes which then might not be sold, as the cost of printing falls to the email buyer. The setter doesn't even have to leave home to post the quiz
I have also sent for quizzes by email which I have then printed and copied to friends who don't have internet (who I know send them in with their payment). I have also forwarded them to friends and family overseas. I don't think any charity would return the entry fee to any contestant who gets a quiz in this way.
When I have set quizzes and advertised them on this site or the Sitesavers I have sent more than 60% of my total entry, and the majority do come back, sometimes with extra donations.
When I enter quizzes email buying saves me the cost of two stamps, which is in fact 72% of the usual entry cost for a charity quiz. This means i will either add that to my entry or I will buy another quiz from somewhere else, so benefitting another charity.
I know that's off the point of Paypal, which I have used to buy but not sell, but come on setters - if you use the internet to promote your quiz then use it better to sell it.