Proton Mail Ext (android-mail-ext)

A fork of Proton Mail for Android with enhancements for sending from external email identities:

• Send from non-Proton addresses through your own SMTP servers
• Stored SMTP server configurations shared across identities
• Sent e-mails are copied into your Proton Sent folder
• Attachments support for external identities
• The composer draft is discarded from Proton Drafts once the external send succeeds

Current status

The sent-copy automation (per-identity labeling and its server-side filter) is currently dormant: its UI was removed from the app, but the underlying functions remain in the codebase for a future re-enable. Push notifications via Google (GMS/FCM) are not available in this fork: the upstream Firebase API key is restricted to the official package name and signing certificate, so this re-signed build cannot obtain an FCM token.

How this fork was made

This fork was built with vibe coding - assisted development where the code is written collaboratively by humans and several different AI coding models. Expect the code to be pragmatic rather than perfect; review anything sensitive before relying on it.

Disclaimer

This project is not affiliated with, endorsed by, or sponsored by Proton AG or any of its subsidiaries. "Proton" and "Proton Mail" are trademarks of their respective owners, used here only to describe the upstream project this fork is based on. The software is provided "AS IS" without warranty of any kind; use it entirely at your own risk. The author is not responsible for any loss, damage or misuse arising from the use of this software.

This build is signed with its own debug and release keys (under keystore/, which is not committed). The package name is ossviber.protonmail.android.

• Install and configure the environment (two options available)
  • Android Studio bundle
  • Standalone Android tools
• Install and configure Java 17+ (not needed for Android Studio bundle as it's included)
• Clone this repository
• Ensure Git LFS is installed (git lfs install) for snapshot test assets
• Setup google-services.json file (a local-dev placeholder is committed)
• Build with any of the following:
  • Debug: ./gradlew assembleDevDebug in a terminal
  • Release: ./gradlew assembleProdRelease -x uploadSentryProguardMappingsProdRelease -x uploadSentryNativeSymbolsForProdRelease
  • Open Android Studio and build the :app module

Pre-built release APKs are published on the releases page.

Original repository: https://github.com/ProtonMail/android-mail