Proton Mail
End-to-end encrypted, open-source, Swiss — the privacy default.
Proton Mail is the most mature encrypted email provider, with over 100 million users and open-source apps on every platform. Mail is end-to-end and zero-access encrypted, it's based in Switzerland under strong privacy law, and it supports OpenPGP so mail with other PGP users is automatically end-to-end encrypted. It has grown into a genuine Gmail replacement with Calendar, Drive, Pass, and VPN in one account, plus a functional free tier.
Strengths
- +End-to-end, zero-access encryption with OpenPGP support
- +Open-source apps, independently audited, Swiss jurisdiction
- +Free tier; custom domains on paid plans
- +Part of a full privacy suite (Calendar, Drive, VPN, Pass)
Trade-offs
- −Encryption to non-Proton, non-PGP contacts needs password-protected mode
- −A hosted service you don't self-host
- −Free-tier storage is modest (1GB)