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K-9 Mail vs Infomaniak Mail: catalog facts
K-9 Mail	Infomaniak Mail
Free Free and open source.	Freemium A free address with 20 GB storage is available; other Infomaniak mail plans are paid.
Android	Android
Open source with a long track record on Android Now the foundation for Thunderbird's official mobile app	Open-source Android client Free address with 20 GB of storage and no ads
Android only, no iOS version Interface is more utilitarian than modern polished mail apps	Only works with Infomaniak-hosted addresses F-Droid version lacks push notifications
Downloadable app	Downloadable app, Hosted service
Open source	Open source
License: Apache-2.0	License: GPL-3.0
Not stated if an account is needed	Account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked October 2, 2026

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