Mozilla Thunderbird vs Spark Mail

Mozilla Thunderbird is a free, open-source email application for Windows, Linux, macOS, and Android. Users can manage multiple accounts separately or combine them in a unified inbox. The app includes calendar, contacts, and task tools; desktop users can also work offline and schedule messages. Its interface is customizable, and it supports third-party add-ons. Thunderbird says it does not put ads in the inbox or sell inbox advertising, and that user donations fund the project. It describes privacy and security as priorities and says its open-source code has been reviewed and improved over 20 years. The application is part of MZLA Technologies Corporation, owned by Mozilla.org. Help and getting-started resources are available for desktop and mobile users, with contributors around the world supporting the project. Thunderbird is available free forever, with donations optional; its listed mobile platform is Android.

Spark Mail is an email app for Android, iOS, macOS, and Windows that helps users focus on important messages. Smart Inbox separates priority mail from other messages, while a unified inbox brings multiple accounts together. It supports IMAP, iCloud, Exchange, Outlook, Yahoo, and Google accounts, as well as offline access, scheduled sending, and calendar tools. Teams can collaborate on email in real time, add private comments and shared information, delegate ownership, track progress, and set deadlines. Spark +AI can translate, summarize, draft, and proofread email; AI Assistant can find information and take action across emails, attachments, meeting notes, and events. AI is disabled by default, and AI features have plan-based monthly quotas. Listed integrations include Asana, Evernote, Google Drive, Microsoft Teams, Notion, Slack, Todoist, Trello, and Zoom, with availability varying by platform. The free plan includes unlimited accounts, Smart Inbox, Smart Notifications, essential email productivity, and Calendar. Plus costs $10 a month per user, and Pro costs $20 a month per user. A 7-day Plus and Pro trial is available when subscribed to directly in the app.