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InboxPager vs Gridlink Mail: catalog facts
InboxPager	Gridlink Mail
Free Free and open source under GPL-3.0.	Free Free and open source under GPL-3.0.
Android	Android
Supports IMAP, POP and SMTP over SSL/TLS Handles attachments and unread-message tracking	Supports JMAP and classic IMAP and SMTP Includes JMAP contacts and calendar support with CardDAV and CalDAV alternatives
Requires an email server that supports SSL/TLS.	Android only A fork of Sterna Mail with a separate release and support path
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0-only	License: GPL-3.0
Not stated if an account is needed	No account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked October 8, 2026

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