KyPost

Email on your own server, on every device you own.

KyPost sits in front of the mailbox you already have. It holds your credentials, sorts mail with a model that runs on your hardware, and gives each phone, laptop, and browser its own key. Pairing a device is one QR scan.

Install the server How it fits together

Open source under the MIT license. Works with any IMAP and SMTP account.

Ky, the KyPost octopus, holding up a phone that shows a pairing QR code

How it fits together

Your devices never learn your mailbox password. They talk to KyPost, and KyPost talks to your provider. Each device hangs off its own arm with its own credential, so you can revoke one without touching the rest.

Your existing mailbox Any IMAP and SMTP provider
KyPost Server Docker, on hardware you control
  • AndroidOpen beta
  • LinuxOpen beta
  • iPhone and MacTesting
  • Web browserIncluded

The interactive map goes deeper: data flows, trust boundaries, and every component.

Open the architecture map

What stays where

The point of running your own server is knowing exactly which machine holds what.

On your server
Mailbox credentials, filter rules, contacts, and the classifier that sorts your inbox. By default nothing about your mail leaves the server for a cloud model.
On each device
A credential minted for that device alone, kept in the platform keystore. Lose a phone, revoke the phone.
Only on enrolled devices
End-to-end encrypted mail is decrypted on the devices you enroll. The server and the push relay never hold the key.

Set up in three steps

Most of an afternoon goes to choosing options, not to installing. The quick start walks through every one.

  1. 1

    Install

    Run the server with Docker Compose, then point it at your IMAP and SMTP provider from the Config screen.

  2. 2

    Pair

    Open Security, then Devices, in the web app and scan the QR code from each native app. Each code expires after 90 seconds.

  3. 3

    Choose

    Turn on device encryption, multi-factor sign-in, local sorting, and push delivery when you want them, one at a time.

Get KyPost

The server first, then a client for each device. Client builds are signed, and every download ships with a digest you can check before installing.

  • Server

    Open beta

    Docker Compose on any Linux host. The quick start covers the environment file, first sign-in, and connecting your mailbox.

    Server quick startSource

  • Android

    Open beta

    A signed APK on every tagged release, with a SHA-256 digest beside it. Play Store and F-Droid listings are coming soon.

    Download the APKInstall notes

  • Linux

    Open beta

    A Flatpak for KDE Plasma and Plasma Mobile from KyPost's own signed remote, for x86_64 and aarch64. Updates arrive through the remote.

    Add the Flatpak remoteSource

  • iPhone and Mac

    Testing

    Coming soon to the App Store. Until then, build it from source with Xcode 26 and pair it from the web app like any other device.

    Build notesSource

  • Web

    Included

    Ships with the server. Open your server's address in any browser to read mail, pair devices, and change settings.