Claws Mail

Lightweight, fast GTK email client with strong PGP support

claws-mail.org
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Price
FreeCompletely free and open source under the GPL.
Works on
Windows, macOS, Linux
Based in
Open-source project
Source code
Open source
Encryption
End-to-end encrypted

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.

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

Claws Mail alternatives

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