Claws Mail is a long-running, GPL-licensed email client written in C on GTK, valued for being lightweight, fast, and highly configurable. Its GnuPG plugins provide robust OpenPGP and S/MIME support for signing and encrypting messages. It handles POP, IMAP, and local mailboxes and stores mail in the plain-text MH format. Development has continued for over two decades, with the 4.x series built on GTK 3. It runs on Linux and other Unix-like systems as well as Windows. The trade-off for its speed is a dated interface and a heavily plugin-driven feature set.
Claws Mail
Lightweight, fast GTK email client with strong PGP support
claws-mail.orgFreeOpen SourceE2E EncryptedWindowsmacOSLinuxOpen-source project
PricingCompletely free and open source under the GPL.
Strengths
- Very lightweight and fast, even on old hardware
- Strong GnuPG-based OpenPGP and S/MIME encryption
- Highly configurable with a large plugin ecosystem
- Free software under the GPL, still actively maintained
Considerations
- Dated, utilitarian interface
- Many features require enabling plugins
- No official first-class macOS build
Listed inEmail Clients
