Thunderbird

Thunderbird is an email and productivity app for people who want their messages, calendars and contacts in one place instead of scattered across browser tabs. It runs on Windows, Mac and Linux, and a mobile version brings the same approach to your phone.

It's funded by user donations. There are no ads in your inbox, no personal data collection, and no quiet use of your private conversations to train AI. It's part of the Mozilla family, a not-for-profit lineage.

• Unified inbox: read mail from every account in one view, or keep accounts separate.
• Tags and filters: mark important messages and organize mail your way.
• Calendars and contacts: handle scheduling and address books without leaving the app.
• Customization: clean by default, but you can adjust the look and workflow to suit you.
• Extensibility: add-ons let you shape it well beyond the defaults.
• Thunderbird Mobile: an open source, privacy-respecting app for email on the go.

It suits anyone juggling several mailboxes, and privacy-minded users who want to own their email rather than rent a locked-down client. Developers and IT staff often pick it for its flexibility. If you're comparing options, browse other email clients or paid rivals like Mailbird and eM Client.

It's free, and stays that way.