K-9 Mail
Overview
• K-9 Mail is a powerful, open-source email client designed for Android.
• It offers a robust alternative to proprietary mail apps by providing a transparent, user-focused experience that is compatible with virtually every email provider using standard IMAP, POP3, or Exchange (via WebDAV) protocols.
Core Features
• Multi-Account Management: Seamlessly manage multiple email accounts from a single interface.
• Unified Inbox: Consolidate messages from all your accounts into one streamlined view.
• Privacy-First Design: K-9 Mail respects your data. It contains no tracking mechanisms and communicates directly with your email provider, ensuring your personal information remains private.
• Synchronization: Stay up-to-date with automatic background synchronization and real-time push notifications.
• Advanced Search: Efficiently find specific messages using both local device indexing and server-side search capabilities.
• End-to-End Encryption: Integrated support for OpenPGP (PGP/MIME) allows for secure communication. To utilize this feature, install the "OpenKeychain: Easy PGP" application.
Support and Troubleshooting
• If you encounter technical issues or have questions regarding the application, visit the official support forum at https://forum.k9mail.app to connect with the community and development team.
Contribute to the Project
• K-9 Mail is now an official part of the Thunderbird family while maintaining its roots as a community-driven, open-source project.
• We invite users to help improve the software by reporting bugs, suggesting features, or contributing code.
• You can access the source code, bug tracker, and project wiki at: https://github.com/thunderbird/thunderbird-android
Join The Open Source Move
• We actively welcome contributions from developers, designers, technical writers, translators, and users interested in quality assurance.
• Join our community to help shape the future of mobile email.
FAQ
Q: Which email providers can I use with K-9 Mail?
A: Because K-9 Mail is designed to be compatible with virtually every standard email provider, it works with almost any service that supports standard IMAP, POP3, or Exchange protocols. Whether you have a personal domain or use a major provider, you should be able to connect your account easily.
Q: Does K-9 Mail support managing multiple email addresses at once?
A: Absolutely. One of the core features of the application is its ability to handle multiple email accounts simultaneously through a single interface, making it very convenient to keep your personal, professional, and secondary accounts organized in one place.
Q: Can I see all my emails in one single list?
A: Yes, you can take advantage of the Unified Inbox feature. This function consolidates incoming messages from all of your configured accounts into one streamlined view, allowing you to stay on top of your correspondence without switching between folders.
Version History
v19.0——3 Jun 2026
K-9 Mail is a 100% open source, privacy focused email client for Android Download the latest version of K-9 Mail to enjoy new features and updates immediately!
*19.0
New:
- Message notification actions can be configured
- Message font size scales with device preferences
- Integrate an easily discoverable way to configure and use Thundermail
Fixed:
- Thunderbird crashed on Android 8 when fetching images
- Accidental swipe in message viewer marked unread email as read
*18.0
New:
- PNG avatars
- Setting to display ISO date/time in message list
- Fixed-width font for composing
Changed:
- Attachment summary moved to header
Fixed:
- "Delete (from notification)" setting did not retain state
- Find folder search hint text was cut off
- User not notified if offline when sending message
- CC/BCC fields were not expanded by default for Reply All
- Crash occurred when retrieving images
- Deleted messages could remain visible in message list
*17.0
New:
- Account avatar customization
- Foldable device support
- Email messages can be printed
- Unified folder account indicator
- Display account avatar in message notifications
Fixed:
- Tap behavior was unreliable in recipient fields
- Device orientiation change duplicated recipient field text
