Thunderbird K-9 Work Jun 2026

Key milestone: On February 21, 2024, the team announced that K-9 Mail version 6.0 officially transitioned to "Thunderbird for Android" Beta. The old branding is being phased out.

Thus, the project internally dubbed was born—a code name representing the transitional phase. The long-term goal? Release a 1.0 version of "Thunderbird for Mobile" that retains K-9’s bones but wears Thunderbird’s skin. thunderbird k-9

While folklore provides the foundation, the specific term "Thunderbird K-9" is largely a product of the modern digital era. The term has surfaced in various subcultures, often as a specific designation in fiction, gaming, or creative writing. Key milestone: On February 21, 2024, the team

| Feature | Thunderbird K-9 | Gmail App | Outlook (Microsoft) | FairEmail | | :--- | :--- | :--- | :--- | :--- | | | Free (Open Source) | Free (Data collected) | Free (Data collected) | Free / Donation | | Tracking | None | Extensive | Extensive | None | | Unified Inbox | Yes | No (Separate tabs) | Yes | Yes | | PGP Encryption | Native | No | No | Advanced | | IMAP Idle (Push) | Yes | Limited (Gmail only) | Yes | Yes | | Calendar Sync | Planned (via DAV) | Yes | Yes | No | | Desktop Sync | Coming (Official) | Web only | Web only | None | The long-term goal