Anonymous registering and use
Use encrypted mailbox by signing up.
Code is open source, which permit to guarantee the robustness of the algorithms and the absence of a backdoor.
Zero data access
Only you and your recipient can read your emails. Not even ProtonMail can read your messages, as it used end to end encryption (E2EE).
Stripped IP address from logs and metadata
All outgoing emails are untraceable to you. ProtonMail does not know your IP, and use its own IP for all emails. Additionally, mailboxes aren’t linked to IP addresses in any way.
No immediate deletion
According to European and Swiss laws, emails are permanently deleted after 6 months only.
Jurisdiction, part of extended 14-eyes
Switzerland is part of the extended 14-eyes alliance, and may exchange data with all countries in the alliance in some specific situations.
Payments in CB
Payments are for the moment not possible in crypto currency. Only CB is possible, which in not in favour of anonymization.
ProtonMail is good at maintaining the privacy of exchanged data, but seems to have room for improvement to better ensure the complete privacy of its users.