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The Bat! vs Claws Mail: catalog facts
The Bat!	Claws Mail
Paid Commercial software from Ritlabs; prices are not listed on the product page.	Free Free and open source under the GPL 3.0 or later.
Windows	Windows, macOS, Linux
Optional encryption of the local message base Blocks tracking pixels and malicious code in mail	Opens and searches enormous mail folders without stalling Plugins for PGP, spam filtering, RSS and calendars ship with it
Windows only Commercial license required	Composes plain text by default; HTML mail sending is deliberately limited The interface is functional and looks like it was designed in 2004
Downloadable app	Downloadable app
Closed source	Open source
License not stated	License: GPL-3.0-or-later
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 21, 2026

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