The best Calendar alternative to Thunderbird is Betterbird, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Thunderbird and many of them are Calendar Apps so hopefully you can find a suitable replacement. Other interesting Calendar App alternatives to Thunderbird are Microsoft Outlook, Evolution, Spark Mail and eM Client.
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.
Germany
EU
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.
United States
Evolution is a personal information management application that provides integrated mail, calendaring, address book and task list functionality.
United States
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.
Ukraine
Looking for a full-featured email client with a modern and easy-to-use interface? Look no further than eM Client. Rated 3 out of 5, eM Client is a popular alternative to Thunderbird, offering all the features you need to manage your email, calendar, tasks, contacts, notes, and chat all in one place.
With support for IMAP, calendar integration, and multiple accounts, eM Client is the perfect choice for users who want a robust email client that can handle all their needs. Whether you're using Windows or Mac, eM Client is the most popular proprietary alternative to Thunderbird, offering a powerful and flexible solution for managing your email and staying organized. Give it a try today and see why so many users are making the switch to eM Client.
CzechiaEU
Mail and calendar for Linux. Gmail and IMAP accounts, Google Calendar, contacts, OpenPGP and S/MIME. GTK4 and libadwaita, written in Rust.
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.
Secure email app for Mac, iPhone, Android and Windows with AI Copilot, PGP encryption, read receipts and one unified inbox.
Singapore
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.
United States
The free Zimbra Desktop client allows you to meld the online and offline worlds – storing and synching your email, calendar, contacts, files and documents in the cloud, yet having them locally accessible when on the road.
United States
Foxmail is a free POP3 and IMAP4 e-mail client in English and Chinese for Windows systems.
China
An enterprise application server that integrates information into a single workspace, integrates also a full mail server
India
