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Thunderbird vs Pegasus Mail: catalog facts
Thunderbird	Pegasus Mail
Free Free forever, funded by donations.	Free Free to use; the developer accepts donations.
Windows, macOS, Linux, Android	Windows
Unified inbox across every account, or each account kept separate, your choice Mail, calendar, contacts and tasks in one application rather than four	Free with no paid tier Decades of continuous development
The interface carries a lot of history and can feel dense next to a webmail tab Major ESR releases have historically been disruptive for add-ons and settings	Windows only Traditional interface and slow release pace
Downloadable app	Downloadable app
Open source	Closed source
License: MPL-2.0	License not stated
No account needed	No account needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked September 20, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.