K-9 Mail review
A capable free Android email client for multi-account and encrypted email.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
K-9 Mail is a free, open-source email client for Android from MZLA Technologies Corporation. It is designed for both novice and power users who manage one or more email accounts on a mobile device. The app supports IMAP and POP3 accounts, push IMAP, unified inboxes, per-account notifications, multiple identities, attachments, signatures, message flagging, keyboard shortcuts, and offline access. It is distributed through Google Play, F-Droid, GitHub Releases, and Amazon under the Apache License 2.0.
For account management, K-9 Mail offers a practical set of controls without tying users to one email provider. Google, Yahoo, AOL, and Microsoft accounts are among the supported integrations, while IMAP and POP3 support broadens its account coverage. A unified inbox brings multiple accounts together, and per-account notifications help separate work, personal, or other email streams. Multiple identities are useful when one account needs different sender details. These features make K-9 Mail a good fit for people who want a focused email app rather than a broader productivity suite.
Security and local access are central to the product’s feature set. TLS encryption protects mail connections, while PGP end-to-end encryption is available through OpenKeychain. The official documentation also confirms local storage of email data, supporting offline access. K-9 Mail is less suitable for users who need desktop or iOS coverage, scheduled sending, or calendar features. Android users seeking a free, open-source client with unified inboxes, notifications, offline access, and encryption should consider it; users wanting broader platform or scheduling support should choose an alternative.
K-9 Mail pros and cons
- Where it wins
- Unified inbox supports multiple email accounts
- Push IMAP, offline access, and per-account notifications
- PGP encryption through OpenKeychain plus TLS mail connections
- Where it doesn't
- Available only on Android
- No send-later feature
- No built-in calendar features
K-9 Mail fact sheet, pricing and score →
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