https://github.com/icd360s-e-v/mail

Secure, end-to-end encrypted email client for desktop and mobile — Flutter, OpenPGP, mTLS, ClamAV, zero local storage
https://github.com/icd360s-e-v/mail

clamav cross-platform dart email-client end-to-end-encryption fluent-ui flutter imap mtls openpgp pgp-mime privacy security smtp zero-knowledge

Last synced: about 1 month ago
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Secure, end-to-end encrypted email client for desktop and mobile — Flutter, OpenPGP, mTLS, ClamAV, zero local storage

Host: GitHub
URL: https://github.com/icd360s-e-v/mail
Owner: ICD360S-e-V
License: agpl-3.0
Created: 2026-04-04T19:23:41.000Z (3 months ago)
Default Branch: main
Last Pushed: 2026-04-19T12:05:58.000Z (2 months ago)
Last Synced: 2026-04-19T12:32:32.804Z (2 months ago)
Topics: clamav, cross-platform, dart, email-client, end-to-end-encryption, fluent-ui, flutter, imap, mtls, openpgp, pgp-mime, privacy, security, smtp, zero-knowledge
Language: Dart
Homepage: https://icd360s.de
Size: 26.5 MB
Stars: 0
Watchers: 0
Forks: 0
Open Issues: 4
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE

Awesome Lists containing this project

README

          


  

  # ICD360S Mail

  **Secure, end-to-end encrypted email for desktop and mobile**

  Your emails are encrypted so only you and your recipient can read them.

  


  [![Release](https://img.shields.io/github/v/release/ICD360S-e-V/mail?style=for-the-badge&logo=github&color=0078D4)](https://github.com/ICD360S-e-V/mail/releases/latest)

  [![Build](https://img.shields.io/github/actions/workflow/status/ICD360S-e-V/mail/build-all-platforms.yml?style=for-the-badge&label=build&color=107C10)](https://github.com/ICD360S-e-V/mail/actions)

  [![License](https://img.shields.io/badge/AGPL--3.0-3F51B5?style=for-the-badge&logo=gnu&logoColor=white)](LICENSE)

  [![REUSE](https://img.shields.io/badge/REUSE-compliant-4CAF50?style=for-the-badge)](REUSE.toml)

  


  

  

  

  

  

  



  [![Flutter](https://img.shields.io/badge/Flutter-02569B?style=flat-square&logo=flutter&logoColor=white)](https://flutter.dev)

  [![OpenPGP](https://img.shields.io/badge/OpenPGP_RFC_9580-333333?style=flat-square&logo=gnuprivacyguard&logoColor=white)](https://www.rfc-editor.org/rfc/rfc9580)

  [![mTLS](https://img.shields.io/badge/Mutual_TLS-006064?style=flat-square&logoColor=white)]()

  [![DANE](https://img.shields.io/badge/DANE+DNSSEC-4527A0?style=flat-square&logoColor=white)]()

  [![WKD](https://img.shields.io/badge/WKD+Autocrypt-1B5E20?style=flat-square&logoColor=white)]()



---

> [!IMPORTANT]

> **Your emails are never stored on your device.** They are fetched live over mutually authenticated TLS and displayed in memory only. No forensic artifact remains after the app closes.

---

## How It Works

```mermaid

graph LR

    A["Your Device"] -->|"mTLS + E2EE"| B["mail.icd360s.de"]

    B -->|"PGP Encrypted"| C["Recipient"]

    B -->|"DANE + DNSSEC"| D["DNS"]

    style A fill:#1565C0,stroke:#0D47A1,color:#fff

    style B fill:#2E7D32,stroke:#1B5E20,color:#fff

    style C fill:#1565C0,stroke:#0D47A1,color:#fff

    style D fill:#4527A0,stroke:#311B92,color:#fff

```

### :eye: What the server sees

- Sender address

- Recipient address

- Subject line

- Date and time

- Message size

### :lock: What's encrypted (E2EE)

- **Message body**

- **Attachments**

- **Attachment names & types**

- **Inner MIME structure**

- **Everything inside the payload**

---

## Features

### :lock: Encryption

- **OpenPGP E2EE** — PGP/MIME (RFC 3156)

- **Native Go engine** — 27 MB in < 1 sec

- **TOFU key pinning** — warns on key change

- **Zero-access storage** — admin can't read mail

- **WKD** — auto key discovery for Thunderbird/ProtonMail

- **Autocrypt** — key exchange in every email

- **Password-protected mail** — AES-256-GCM for external recipients

### :shield: Authentication

- **Mutual TLS** — per-user client certificates

- **Device approval** — admin-controlled enrollment

- **Remote revocation** — instant wipe on revoke

- **PIN unlock** — randomized keypad layout

- **DANE + DNSSEC** — verified transport

- **ARC signing** — auth preserved on forward

### :see_no_evil: Privacy

- **RAM-only cache** — zero disk, wiped on lock

- **Self-hosted DoH** — no Google, no Cloudflare

- **Header stripping** — IP/hostname removed from outgoing

- **PII-safe logging** — auto-redaction of sensitive data

- **No telemetry** — zero analytics, zero tracking

### :bar_chart: Security Monitoring

- **10 health checks** every 30 minutes

- SPF, DKIM, DMARC, MTA-STS, TLS-RPT

- CAA, DNSSEC, DANE (TLSA)

- IPv4/IPv6 blacklist (43 providers)

- **Recipient security** in compose — E2EE / DANE / TLS / Plaintext

---

## Cryptography

> [!NOTE]

> All cryptographic operations use modern, audited standards. No legacy algorithms.

| Component | Standard |

|:---|:---|

| :key: Signing | Ed25519 (EdDSA) |

| :closed_lock_with_key: Encryption | X25519 / ECDH (Curve25519) |

| :envelope: Messages | OpenPGP (RFC 9580, PGP/MIME RFC 3156) |

| :bank: Vault | AES-256-GCM + Argon2id (64 MiB / 3 iters / 4 threads) |

| :satellite: Transport | Mutual TLS + DANE (TLSA 3 1 1) + DNSSEC |

| :mag: Key discovery | WKD + Autocrypt Level 1 |

---

## Download

> [!TIP]

> All downloads are served over HTTPS with cryptographically signed version verification.

### Desktop




























Linux packages: DEB, RPM, tar.gz

| Format | Download |

|:---|:---|

| DEB (Ubuntu/Debian) | [icd360s-mail.deb](https://mail.icd360s.de/downloads/mail/linux/icd360s-mail.deb) |

| RPM (Fedora/RHEL) | [icd360s-mail.rpm](https://mail.icd360s.de/downloads/mail/linux/icd360s-mail.rpm) |

| tar.gz | [icd360s-mail-linux.tar.gz](https://mail.icd360s.de/downloads/mail/linux/icd360s-mail-linux.tar.gz) |

### Mobile



















Android flavors: F-Droid, Samsung, Huawei, Google Play

| Flavor | ARM64 | ARMv7 | x86_64 |

|:---|:---|:---|:---|

| Universal | [Download](https://mail.icd360s.de/downloads/mail/android/universal/app-arm64-v8a-universal-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/universal/app-armeabi-v7a-universal-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/universal/app-x86_64-universal-release.apk) |

| F-Droid | [Download](https://mail.icd360s.de/downloads/mail/android/fdroid/app-arm64-v8a-fdroid-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/fdroid/app-armeabi-v7a-fdroid-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/fdroid/app-x86_64-fdroid-release.apk) |

| Samsung | [Download](https://mail.icd360s.de/downloads/mail/android/samsung/app-arm64-v8a-samsung-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/samsung/app-armeabi-v7a-samsung-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/samsung/app-x86_64-samsung-release.apk) |

| Huawei | [Download](https://mail.icd360s.de/downloads/mail/android/huawei/app-arm64-v8a-huawei-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/huawei/app-armeabi-v7a-huawei-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/huawei/app-x86_64-huawei-release.apk) |

| Google Play | [Download](https://mail.icd360s.de/downloads/mail/android/googleplay/app-arm64-v8a-googleplay-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/googleplay/app-armeabi-v7a-googleplay-release.apk) | [Download](https://mail.icd360s.de/downloads/mail/android/googleplay/app-x86_64-googleplay-release.apk) |

---

## Building from Source

```bash

git clone https://github.com/ICD360S-e-V/mail.git

cd mail && flutter pub get

flutter run -d macos    # or: windows, linux

```

Platform requirements

| Platform | Requirements |

|:---|:---|

| All | Flutter 3.41+, Dart 3.6+ |

| Android | Java 17, Android SDK |

| iOS/macOS | Xcode 15+ |

| Linux | `libgtk-3-dev`, `libsecret-1-dev`, `libjsoncpp-dev` |

| Windows | Visual Studio 2022 with C++ workload |

---

## About ICD360S e.V.

[ICD360S e.V.](https://icd360s.de) is a registered German nonprofit (*eingetragener Verein*). Every active member receives a free, secure `@icd360s.de` email account with E2E encryption and cross-platform access.

> [!CAUTION]

> The live service at `mail.icd360s.de` is available **exclusively to members**. This repository contains the open-source code — the operational service is private.

---



[:scroll: Security Policy](SECURITY.md) · [:wheelchair: Accessibility](ACCESSIBILITY.md) · [:handshake: Contributing](CONTRIBUTING.md) · [:page_facing_up: License](LICENSE)




**[ICD360S e.V.](https://icd360s.de)** · Amtsgericht Memmingen, VR 201335

[kontakt@icd360s.de](mailto:kontakt@icd360s.de) · [Impressum](https://icd360s.de/impressum/) · [Datenschutz](https://icd360s.de/datenschutz/)

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