Ferroxide

A community fork of emersion/ferroxide

Primary changes:

• Caldav
• Tor and proxies
• Custom config directory

Original Hydroxide ReadMe

A third-party, open-source ProtonMail bridge. For power users only, designed to run on a server.

ferroxide supports CardDAV, CalDAV, IMAP and SMTP.

Rationale:

• No GUI, only a CLI (so it runs in headless environments)
• Standard-compliant (we don't care about Microsoft Outlook)
• Fully open-source

Feel free to join the IRC channel: #emersion on Libera Chat.

How does it work?

ferroxide is a server that translates standard protocols (SMTP, IMAP, CardDAV, CalDAV) into ProtonMail API requests. It allows you to use your preferred e-mail clients and git-send-email with ProtonMail.

+-----------------+             +-------------+  ProtonMail  +--------------+
|                 | IMAP, SMTP  |             |     API      |              |
|  E-mail client  <------------->  ferroxide  <-------------->  ProtonMail  |
|                 |             |             |              |              |
+-----------------+             +-------------+              +--------------+

Setup

Go

ferroxide is implemented in Go. Head to Go website for setup information.

Installing

Start by installing ferroxide:

go install github.com/acheong08/ferroxide/cmd/ferroxide@latest

Then you'll need to login to ProtonMail via ferroxide, so that ferroxide can retrieve e-mails from ProtonMail. You can do so with this command:

ferroxide auth <username>

Once you're logged in, a "bridge password" will be printed. Don't close your terminal yet, as this password is not stored anywhere by ferroxide and will be needed when configuring your e-mail client.

Your ProtonMail credentials are stored on disk encrypted with this bridge password (a 32-byte random password generated when logging in).

Usage

ferroxide can be used in multiple modes.

Don't start ferroxide multiple times, instead you can use ferroxide serve. This requires ports 1025 (smtp), 1143 (imap), 8080 (carddav) and 8081 (caldav).

SMTP

To run ferroxide as an SMTP server:

ferroxide smtp

Once the bridge is started, you can configure your e-mail client with the following settings:

• Hostname: localhost
• Port: 1025
• Security: none
• Username: your ProtonMail username
• Password: the bridge password (not your ProtonMail password)

CardDAV

You must setup an HTTPS reverse proxy to forward requests to ferroxide.

ferroxide carddav

Tested on GNOME (Evolution) and Android (DAVDroid).

CalDAV

ferroxide caldav

Tested on GNOME (Evolution), Thunderbird, KOrganizer.

IMAP

⚠️ Warning: IMAP support is work-in-progress. Here be dragons.

For now, it only supports unencrypted local connections.

ferroxide imap

License

MIT