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Claws Mail vs aerc: catalog facts
Claws Mail	aerc
Free Free and open source under the GPL 3.0 or later.	Free Free and open source under the MIT licence.
Windows, macOS, Linux	macOS, Linux, Command line
Opens and searches enormous mail folders without stalling Plugins for PGP, spam filtering, RSS and calendars ship with it	Composes in an embedded terminal, so you can read other mail while replying Built for the git mailing-list patch workflow, with diff highlighting and repo tabs
Composes plain text by default; HTML mail sending is deliberately limited The interface is functional and looks like it was designed in 2004	Terminal only, with vim-style keybindings to learn HTML mail rendering is a terminal browser, so complex newsletters look poor
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0-or-later	License: MIT
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked September 21, 2026	Official website Full listing and sources Checked September 21, 2026

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