GitHub - JB-SelfCompany/Tyr: True P2P Email on top of Yggdrasil Network for Android

📸 Screenshots

🌐 What is Tyr?

We're taught that email must go through servers. Why? Because the Internet was built around centralized infrastructure. Every email you send travels through multiple servers - your provider's server, maybe a few relay servers, and finally your recipient's provider's server. Each hop is a potential point of surveillance, censorship, or failure.

Even "encrypted" email solutions still rely on these centralized servers. They encrypt the message content but the metadata - who you're talking to, when, how often - is visible to anyone watching the servers.

But there is a network, called Yggdrasil, that gives everyone a free IPv6 and doesn't need a blessing from your ISP. We finally have this possibility to use true P2P email. And moreover, this network has strong encryption to protect all data that flows from one IP to another.

Tyr brings true peer-to-peer email to your Android device using these unusual conditions. Unlike traditional email clients, Tyr doesn't need:

• ❌ Centralized mail servers (the connections are straight P2P)
• ❌ Message encryption layers (the network takes care of that)
• ❌ Port forwarding or STUN/TURN servers (Yggdrasil handles NAT traversal)

✨ Features

🛠️ How It Works

graph LR
    A[DeltaChat/ArcaneChat] -->|SMTP/IMAP| B[Tyr Service]
    B -->|Yggmail Protocol| C[Yggdrasil Network]
    C -->|P2P Encrypted| D[Recipient's Tyr]
    D -->|SMTP/IMAP| E[Recipient's Chat App]

Tyr runs a complete email server right on your Android device, using the Yggdrasil network for transport. The Yggmail mail server (built in Go) is embedded as a library inside the app and runs as a foreground service.

On top of Yggdrasil, it provides standard SMTP and IMAP protocols on localhost (127.0.0.1:1025 and 127.0.0.1:1143). Any email client can connect to these ports - but we recommend DeltaChat or ArcaneChat for the best P2P messaging experience.

📬 Mail Address Format

Every Tyr installation generates unique Ed25519 cryptographic keys. Your mail address is derived from your public key:

<64-hex-characters>@yggmail

This means your identity is cryptographically verifiable and cannot be spoofed.

📱 Quick Start

Setting up DeltaChat/ArcaneChat

Option 1: Automatic Setup (Recommended)

1. Install Tyr and complete the onboarding (set password, configure peers)
2. Start the Yggmail service in Tyr
3. Install DeltaChat or ArcaneChat
4. In Tyr's main screen, tap "Setup DeltaChat/ArcaneChat"
5. Tyr will automatically open your chat app with pre-configured settings
6. Complete the setup and start chatting!

Option 2: Manual Setup

If automatic setup doesn't work:

1. Complete Tyr onboarding and start the service
2. Copy your mail address from Tyr's main screen (looks like abc123...@yggmail)
3. In DeltaChat/ArcaneChat, create a new profile
4. Tap "Use a different server"
5. Enter your Yggmail address and the password you set in Tyr
6. Tap "✓" to complete setup

Setting up Other Email Clients

Tyr works with any standard email client. For K-9 Mail, Thunderbird Mobile, or FairEmail:

1. Complete Tyr onboarding and start the service
2. In Tyr's main screen, tap "Email Client Setup" card for detailed instructions
3. Configure your email client with:
   • Email: Your mail address from Tyr (e.g., abc123...@yggmail)
   • Password: The password you set during Tyr onboarding
   • IMAP: 127.0.0.1:1143 (no encryption)
   • SMTP: 127.0.0.1:1025 (no encryption)

QR Code Sharing: Tap the "QR Code" button in Tyr to generate a QR code for your mail address. You can share it via the system share sheet to quickly exchange addresses with contacts.

Important: Tyr must be running for your email client to send and receive messages. Enable auto-start in Tyr settings for seamless experience.

🔒 Security Features

• Password Encryption: Android Keystore System with AES-256-GCM
• Automatic Keystore Recovery: Handles Android Keystore issues on Samsung and other devices
• Network Encryption: All P2P communications encrypted by Yggdrasil Network
• Local-Only Access: SMTP/IMAP ports bound to localhost only
• Cryptographic Identity: Ed25519 keys ensure your mail address cannot be spoofed
• Encrypted Backups: Configuration and keys backed up with password protection
• Privacy-First Push: Instant notifications without third-party push services or metadata exposure

🏗️ Building from Source

Prerequisites

• Android Studio (latest version)
• JDK 17
• Android SDK (API 23-36)
• Go 1.21+ and gomobile (only if rebuilding yggmail.aar)

Build Commands

# Clone the repository
git clone https://github.com/JB-SelfCompany/Tyr.git
cd Tyr

# Build debug APK
./gradlew assembleDebug

# Install to connected device
./gradlew installDebug

APKs will be in app/build/outputs/apk/debug/ or app/build/outputs/apk/release/

Rebuilding yggmail.aar (optional)

cd ../yggmail/mobile

# Windows
..\build-android.bat

# Unix
gomobile bind -target=android -androidapi 23 -javapkg=com.jbselfcompany.tyr -ldflags="-checklinkname=0" -o yggmail.aar .

Then copy yggmail.aar to Tyr/app/libs/

🔧 Technical Details

🤝 Related Projects

• Yggmail: The mail transfer agent that powers Tyr
• Mimir: P2P messenger on Yggdrasil (sister project)
• Yggdrasil Network: The mesh network infrastructure
• DeltaChat: Recommended email-based messenger client
• ArcaneChat: Alternative email-based messenger client
• K-9 Mail: Open-source email client for Android
• Thunderbird Mobile: Mozilla's mobile email client (based on K-9)
• FairEmail: Privacy-oriented email client for Android

📄 License

Tyr is open source software. The Yggmail library uses Mozilla Public License v. 2.0.

See LICENSE file for full details.

🌟 Why P2P Email Matters

Censorship Circumvention: Connect to any of hundreds of available Yggdrasil nodes, host your own, or even build a private network. Email freedom is literally in your hands.

Privacy by Design: No metadata collection, no server logs, no third-party surveillance. Your conversations belong to you.

Decentralization: No single point of failure, no corporate control. True peer-to-peer architecture.