Top Alternatives to Zimbra Desktop

Thunderbird is a free, open-source email client developed by the Mozilla Foundation, offering robust features for managing multiple email accounts, integrated chat, and RSS feeds. Known for its extensibility and focus on user privacy and security.

Microsoft Outlook is a comprehensive personal information manager designed for managing email, contacts, calendars, and tasks.

Mailbird is a powerful and intuitive desktop email client for Windows, designed to streamline your email workflow and centralize your digital communication with a clean interface and built-in app integrations.

Apple Mail is the default email client for macOS, iOS, and watchOS, offering a seamless and integrated email experience across Apple devices with features like rich text editing, multiple account support, and robust organization tools.

eM Client is a comprehensive email client for Windows and macOS, integrating email, calendar, contacts, tasks, and chat into a single application. It offers robust features for managing multiple accounts, advanced security options, and a user-friendly interface, making it a powerful alternative to other popular email applications.

Evolution is a comprehensive personal information manager for the GNOME desktop environment, designed to manage emails, contacts, calendars, and tasks. It provides a unified interface for various communication and organizational needs.

Postbox is a powerful and customizable email client designed for professionals managing high volumes of email. It offers robust features for organizing, searching, and managing multiple accounts efficiently, enhancing productivity through a clean interface and advanced tools.

QupZilla is a free and open-source web browser designed for general users, emphasizing speed, privacy, and a clean user interface. It leverages the powerful QtWebEngine to deliver a modern browsing experience while remaining lightweight and resource-efficient.

UC Browser is a feature-rich mobile web browser designed for speed and efficiency. It offers a suite of tools including a built-in ad-blocker, download manager, and various integrations, aiming to provide a smooth and optimized browsing experience on mobile devices.

Mailspring is a modern, fast, and free desktop email client for Mac, Windows, and Linux. It offers a beautiful interface, powerful features like unified inbox, email tracking, and broad platform support for an enhanced email experience.

Claws Mail is a powerful yet lightweight, open-source email and news client built on GTK+. It's known for its speed, stability, rich feature set, and high degree of customization, making it an excellent choice for users demanding control and efficiency.

EssentialPIM is a versatile personal information manager designed to help you organize your life. It allows you to manage appointments, tasks, notes, contacts, passwords, and more, all within a single, customizable application available for desktop and mobile platforms.

The Bat! is a secure and powerful email client for Windows designed for users who prioritize privacy, speed, and efficient email management, especially for handling large mail volumes.

Airmail is a powerful and lightning-fast email client designed for macOS and iOS. It aims to provide a clean, modern interface with advanced features for managing multiple email accounts efficiently.

Mutt is a highly configurable, text-based email client for Unix-like systems. It offers powerful features for advanced users who prefer a lightweight and efficient email management experience directly from the command line.

Iridium Browser is a security-focused web browser built upon the Chromium codebase. It prioritizes user privacy by significantly reducing data transmission to Google and other servers, while incorporating enhanced security features and utilizing the latest secure technologies for a safer browsing experience.

Slimjet is a fast, secure, and smart web browser built on the Blink rendering engine, powered by Chromium. It offers a suite of built-in tools like a downloader, ad blocker, and form filler, enhancing the browsing experience.

OpenProject is a powerful, web-based open-source project management software designed for teams of all sizes. It offers comprehensive tools for managing projects, tasks, teams, and communication in one centralized platform. Ideal for organizations prioritizing collaboration, flexibility, and data control.

KMail is a powerful and flexible email client tightly integrated with the Kontact personal information manager suite. Part of the KDE ecosystem, it offers robust features for managing your email, including strong encryption options, support for multiple protocols like IMAP, POP3, and Exchange, and seamless integration with other Kontact components like the calendar and address book.

Kontact is a comprehensive personal information management suite from KDE combining email, contacts, calendar, tasks, and news in one integrated application. It offers robust synchronization options and supports various protocols.

Feng Office is a robust open-source web-based platform designed to enhance team collaboration and productivity. It integrates project management, task tracking, document management, and CRM capabilities into a single solution, catering to businesses of various sizes.

AOL Mail is a free web-based email service offering reliable communication tools, generous storage, and integrated features like calendar and cloud storage, suitable for individuals and small businesses seeking a straightforward email solution.

Polymail is an advanced email client for macOS and iOS, built to enhance productivity for professionals using Gmail. It goes beyond basic email functions with robust features like email tracking, scheduling, and team collaboration tools, all wrapped in a sleek and intuitive interface.

<p>MailMate is a powerful, keyboard-centric IMAP email client for macOS designed for users who demand advanced email management capabilities and a highly customizable workflow, featuring strong Markdown integration and robust search features.</p>

Microsoft Mail and Calendar is the default email and calendar client included with Windows, providing integrated tools to manage your communications and schedule.