K-9 Mail

Free#75 of 142 in Email ClientsEmail Apps

K-9 Mail: A capable free Android email client for multi-account and encrypted email. Ranked #75 of 142 in Email Clients by our editors (3.0/10); pricing: Free plan; best for android users wanting free open-source secure email.

3.0/10★★☆☆☆Editor score

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At a glance

• Editor score
  3.0 / 10
• Pricing
  Free plan
• Best for
  Android users wanting free open-source secure email
• Free plan
  Yes
• Paid from
  Free
• App coverage
  Mobile
• Facts checked
  24 Sep 2026

• 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

Our verdict on K-9 Mail

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.

Your product? Our editors can test K-9 Mail in depth and publish a review, labelled as paid · from $149/mo →

K-9 Mail pricing

K-9 Mail fact sheet

Alternatives to K-9 Mail

• Mozilla ThunderbirdA capable free client for multi-account email, offline access, and desktop productivity tools.9.4
• Zoho MailA flexible hosted email service with free access, migration tools, and Zoho collaboration options.9.2
• Apple MailA capable Apple-focused email client with unified inboxes, scheduling, privacy controls, and AI assistance.9.1

See all K-9 Mail alternatives →

Featured on iTechGuides

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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

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Last updated 7 Oct 2026 · How we research and update