Compare software

Mailspring vs Claws Mail: catalog facts
Mailspring	Claws Mail
Freemium The client is free and open source. Mailspring Pro is a monthly subscription that adds…	Free Free and open source under the GPL 3.0 or later.
Windows, macOS, Linux	Windows, macOS, Linux
Unified inbox, snooze, send later, rules and templates in the free tier C++ sync engine keeps memory and battery use down for an Electron app	Opens and searches enormous mail folders without stalling Plugins for PGP, spam filtering, RSS and calendars ship with it
Read receipts and link tracking are paid, and are tracking features Electron, so still heavier than a native client	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
Open source	Open source
License: GPL-3.0	License: GPL-3.0-or-later
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

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