I email Buxton Mountain Rescue quiz but only after payment made via Paypal. You don't need to have an account with them, payment is easy. I am informed by Paypal when payment has been made and I see no payment details, just name, address and email address. No postage required and can then be returned by email attachment or post if preferred. Applicants get their quiz sooner, the charity doesn't lose out on the ones that are not returned for whatever reason.
If only emailed without payment as you are suggesting, the applicant still has postage to pay for its return with payment. My method does give the opportunity of receiving and returning the quiz with NO postage.