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Sympa vs Schleuder: catalog facts
Sympa	Schleuder
Free Free and open source under the GPL-2.0 licence.	Free Free and open source under the GPL-3.0 licence.
Self-hosted, Command line	Self-hosted
Designed for lists with tens of thousands of subscribers Handles subscription, moderation and archives in one package	OpenPGP encryption for group email Can send and receive mail to and from non-subscribers
Requires running and configuring your own mail server Setup is aimed at experienced system administrators	Members need to manage OpenPGP keys Requires running your own mail server
Self-hosted	Self-hosted
Open source	Open source
License: GPL-2.0	License: GPL-3.0
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

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