From their pricing page[0] it looks like their highest-priced plan only goes to 20GB. That's an order of magnitude too little for me just for the current size of all my mail.

(And no, I don't want to clean up 20+ years of email. I want to pay someone else to handle archiving and indexing it and not think about it.)

[0] https://protonmail.com/pricing

Professional can go up to 500GB, Plus only goes to 20GB, but that's set manually in their dashboard.