There are many alternatives to K-9 Mail for Android if you are looking for a replacement. The best Android 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 many of them are available for Android so hopefully you can find a suitable replacement. Other interesting Android alternatives to K-9 Mail are FairEmail, Microsoft Outlook, Spark Mail and Infomaniak kMail.
Cross-platform email client supporting multiple identities, chat, and strong filtering. Extend functionality with add-ons like RSS/Atom feed readers and PGP support.
Open-source, privacy-focused email client offering features such as encryption via OpenPGP and S/MIME, unlimited accounts, a unified inbox, customizable settings, and reformatted emails to prevent phishing. Supports two-way synchronization and provides Pro features for additional customization.
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.
Privacy-focused Swiss email system provides 20 GB free storage, supports custom domains and unlimited storage, syncs contacts and calendars, is ad-free, and is part of a secure productivity suite used by over a million users across Europe on all devices.
A secure, cross-platform email client with a unified inbox, built-in PGP encryption, and optional AI. Use powerful AI when you want it or turn it off completely. Your email, your control.
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.
No-frills, easy to use, easy to maintain Email client for Android based on the JSON Meta Application Protocol (JMAP).
Email by Edison (formerly Email by EasilyDo) is a brand new, elegantly designed, universal mail app to manage unlimited mail accounts.
Shortwave is an email app that takes the pain out of managing your inbox, making it effortless to stay organized, productive, and responsive.
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.
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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