Mailspring Libre comes completely free of charge. No plans, no upgrades, no money.
Free as in freedom. UI and app licensed under the GPLv3.
All telemetry is disabled. No centralized server is needed.
Mailspring is beautiful and functional. Themes and plugins allow for limitless customization.
Mailspring Libre uses Electron to work across all major platforms: macOS, Linux, and Windows.
The sync engine, MailSync, is proprietary, and while we're working on replacing it, it probably won't happen anytime soon.