Required an one time payment for free accounts
Protonmail should change requirements to get a free email be required a one time payment to combat fraud and stop protonmail's domains being blacklisted by email providers, I can't afford the current pricing but for a low one time fee to have a free email from you I would gladly pay, please consider this so your service is less used for nefarious purposes.
if they would do this might loose lots of People, and they might go other places.
The idea is stupid. When the user would need to pay for the account then he/she would probably resign from it. There is already a paid plan, so another is not nessecary, plus paying for a free account may cause a big facial and probably legal issues