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.
Cross-platform email client supporting multiple identities, chat, and strong filtering. Extend functionality with add-ons like RSS/Atom feed readers and PGP support.
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.
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.
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.
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.
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.
Canary can write your emails, prioritize what needs attention, silence spam & much more. Say hello to your Inbox Copilot!
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.
Email by Edison (formerly Email by EasilyDo) is a brand new, elegantly designed, universal mail app to manage unlimited mail accounts.
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.
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.
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.
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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