If I have two accounts, I can transfer lots of spam mails between each other and attack this system. So IMO, the fee should not be retrievable and must be destroyed for ever.
I think there is the need on market, we honestly need a CLEAN email and almost everyone wanna show how they are important and “Don’t disturb me if no important things”. The VIPs on social media may show off their high email bar, 10$,100$ etc. LOL