Top Alternatives to Spark

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.

K-9 Mail is a free and open-source email client for Android, renowned for its focus on privacy, security, and extensive customization options. It supports multiple account types including IMAP, POP3, and Exchange.

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.

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.

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.

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.

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.

FairEmail is a highly privacy-focused and feature-rich open-source email client for Android. It champions user control, offering extensive customization options, robust security features like end-to-end encryption, and a unified inbox experience, all while being ad-free and lightweight.

Spike transforms your inbox into a collaborative workspace, merging email, chat, calls, and documents into a single, streamlined interface. It redefines communication by making email more conversational and integrates project management tools, file sharing, and calendar functionality to boost productivity for individuals and teams, aiming to be a true all-in-one productivity hub.

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.

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

TypeApp is a sophisticated mobile email client designed for managing multiple email accounts effortlessly. It provides a unified inbox, push notifications, calendar integration, and a range of features to enhance email productivity on the go.