Correct, the former. There are no other open-source email servers (or closed even) that does the former that we know of. The deep-dive write-up is here if you want to read more https://forwardemail.net/encrypted-email.

Edit: It matters because if someone has access to the filesystem, or our MongoDB database, then they still can't read/write to your email mailbox because they don't have your IMAP password (which we only show to you _once_ for 30 seconds and render in-memory). We use ChaCha20-Poly1305 encryption on the SQLite mailboxes (which is generally considered quantum-secure[0]). Passwords are generated[1] via Node.js `crypto.pbkdf2`.

[0]: https://crypto.stackexchange.com/a/90311 [1]: https://github.com/forwardemail/forwardemail.net/blob/d537fc...