K-9 Mail Alternatives for Windows

K-9 Mail is not available for Windows but there are plenty of alternatives that runs on Windows with similar functionality. The best Windows alternative is Thunderbird, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to K-9 Mail and 19 are available for Windows so hopefully you can find a suitable replacement. Other interesting Windows alternatives to K-9 Mail are Betterbird, Microsoft Outlook, Spark Mail and Mailspring.

filter to find the best alternatives

K-9 Mail alternatives are mainly Email Clients, but if you're looking for Calendar Apps or Contact Managers you can filter on that. Other popular filters include iPhone, Linux, Windows, Android and Android + Open Source. These are just examples - use the filter bar below to find more specific alternatives to K-9 Mail.
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Alternatives list

  1. Thunderbird icon

    Thunderbird

     2543 likes

    Cross-platform email client supporting multiple identities, chat, and strong filtering. Extend functionality with add-ons like RSS/Atom feed readers and PGP support.

    86 Thunderbird alternatives

    Cost / License

    Application types

    Platforms

    • Mac
    • Windows
    • Linux
    • Android
    • BSD
    • AppImageHub
    • Snapcraft
    • Flathub
    • PortableApps.com
    • F-Droid
    • Haiku
    • Homebrew
    • Chocolatey
    Thunderbird screenshot 1
     
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    2
    Comments about Thunderbird as an Alternative to K-9 Mail
    Tubby 9417
    Positive
    0

    A really great client used by many, popular because it supports almost every mail provider (not proton ?), and mail providers provide documentation to integrate with Thunderbird. I recommand

    Diatomee
    0

    Afaik the Thunderbird for Android and K-9 mail are developed by the same team now and have the same infrastructure under the hood, therefore it doesn't make any difference which one you choose.

    Thunderbird icon
    Thunderbird icon
    • Thunderbird is Free and Open SourceK-9 Mail is also Free and Open Source
    • Thunderbird is CustomizableK-9 Mail is not according to our users
  2. Betterbird icon

    Betterbird

     73 likes

    Betterbird, a soft fork of Mozilla Thunderbird, improves user experience with advanced features, bug fixes, security patches, and multi-row descriptions similar to Outlook. Compatible with multiple platforms and can be used alongside Thunderbird, sharing the same profile.

    28 Betterbird alternatives

    Cost / License

    • Free
    • Open Source

    Application type

    Platforms

    • Mac
    • Windows
    • Linux
    • Flathub
    • Chocolatey
    Betterbird screenshot 1
     
  4. Microsoft Outlook icon

    Microsoft Outlook

     397 likes

    Streamline emails, calendars, contacts, and task management with a smart inbox prioritizing critical messages. Includes calendar scheduling, third-party app integration like Facebook, Dropbox, and Trello, and support for Microsoft Exchange, Outlook.com, and Gmail, ensuring efficient task and email handling.

    126 Microsoft Outlook alternatives

    Cost / License

    • Paid
    • Proprietary

    Application types

    Platforms

    • Mac
    • Windows
    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • Apple Watch
    • Android Wear
    Outlook 365 on Windows
     
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    2
    Comments about Microsoft Outlook as an Alternative to K-9 Mail
    Guest
    Negative
    5

    Microsoft Office Outlook has more vulnerabilities and so far, seems more of a memory hogger on my device than K-9 Mail. Thank you, K-9 Mail!

    Review by a new / low-activity user.
    Guest
    Negative
    0

    If you use outlook for another email it will strore the password on a Microsoft server

    Review by a new / low-activity user.
    Microsoft Outlook icon
    Microsoft Outlook icon
    • Microsoft Outlook is Paid and ProprietaryK-9 Mail is Free and Open Source
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  6. Spark Mail icon

    Spark Mail

     138 likes

    E-mail app with all the great features: swipes (long/short), snooze, add (multiple) attachments from the cloud, support for various e-mail services and more.

    62 Spark Mail alternatives

    Cost / License

    • Freemium
    • Proprietary

    Application type

    Platforms

    • Mac
    • Windows
    • Android
    • iPhone
    • iPad
    • Apple Watch
    Spark Mail screenshot 1
     
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    1
    Comments about Spark Mail as an Alternative to K-9 Mail
    abogawat
    Positive
    0

    Spark is one of the most polished email clients out there, with multi-platform support and an excellent feature set. The free version is good enough for most people.

    Spark Mail icon
    Spark Mail icon
    • Spark Mail is Freemium and ProprietaryK-9 Mail is Free and Open Source
  7. Mailspring icon

    Mailspring

     114 likes

    Boost your productivity and send better email with Mailspring, a beautiful, fast email client for Mac, Windows, and Linux. Mailspring is free to use and an optional pro version adds read receipts, send later, reminders and more.

    43 Mailspring alternatives

    Cost / License

    Application type

    Platforms

    • Mac
    • Windows
    • Linux
    • Arch Linux
    • Fedora
    • Ubuntu
    Clean design with integrated search and swipe gestures
     
  8. Claws Mail icon

    Claws Mail

     106 likes

    Email and news client on GTK+ foundation featuring quick performance, extensible plugins, secure protocols, advanced filtering, strong folder and contact management, lightweight design, powerful search, customizable interface, multi-language support, and encryption.

    62 Claws Mail alternatives

    Cost / License

    • Free
    • Open Source

    Application types

    Platforms

    • Windows
    • Linux
    • BSD
    The main window
     
  10. Canary Mail icon

    Canary Mail

     28 likes

    Canary can write your emails, prioritize what needs attention, silence spam & much more. Say hello to your Inbox Copilot!

    62 Canary Mail alternatives

    Cost / License

    • Freemium
    • Proprietary

    Application type

    Platforms

    • Mac
    • Windows
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • Apple Watch
    Canary Mail screenshot 1
     
  11. BlueMail icon

    BlueMail

     33 likes

    BlueMail is a modern, mobile first, powerful Email management tool with a sleek design, unified inbox and support for all your accounts: IMAP,Exchange,POP3.

    32 BlueMail alternatives

    Cost / License

    • Free Personal
    • Proprietary

    Application type

    Platforms

    • Mac
    • Windows
    • Linux
    • Android
    • iPhone
    • Chrome OS
    • Android Tablet
    • iPad
    • Apple Watch
    BlueMail screenshot 1
     
  12. TypeApp icon

    TypeApp

     30 likes

    TypeApp is an all-free, beautifully designed, universal email app, capable of managing unlimited number of mail accounts from various providers, allowing for smart push notifications while enabling personalization across multiple email accounts.

    54 TypeApp alternatives

    Cost / License

    • Free Personal
    • Proprietary

    Application type

    Platforms

    • Mac
    • Windows
    • Linux
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • Android Wear
    • Kindle Fire
    TypeApp screenshot 1
     
  13. LucaMail icon

    LucaMail

     9 likes

    LucaMail is an open source, cross-platform email client. LucaMail is developed to provide cross-platform alternative to Email Clients that are really exists. LucaMail focuses on modern technologies as well as maintaining a user-friendly UI.

    Cost / License

    Application type

    Alerts

    • Discontinued

    Platforms

    • Mac
    • Windows
    • Linux
    LucaMail screenshot 1
     
  14. Superhuman Mail icon

    Superhuman Mail

     3 likes

    Productivity-centered email application streamlines inbox management, uses AI for drafting responses, automates snippets, summarizes conversations, enables timely sends, integrates calendar and CRM, and includes collaborative features like live views and comments.

    54 Superhuman Mail alternatives

    Cost / License

    • Paid
    • Proprietary

    Application type

    Platforms

    • Mac
    • Online
    • iPhone
    • iPad
    • Android
    • Android Tablet
    • Windows
    Superhuman Mail screenshot 1
     
  15. Nylas Mail Lives icon

    Nylas Mail Lives

     3 likes

    Nylas Mail Lives is a fork of Nylas Mail that fixes many longstanding issues, improves the client experience, and is committed to publish new releases.

    Cost / License

    • Free
    • Open Source (MIT)

    Application type

    Alerts

    • Discontinued

    Platforms

    • Mac
    • Windows
    • Linux
    • Self-Hosted
    Nylas Mail Lives screenshot 1
     
12 of 19 K-9 Mail alternatives