Balsa (email client)
Balsa displaying built-in GPG capabilities
|License||GNU General Public License|
Balsa has a graphical front end, support for MIME attachments coming and going, directly supports POP3 and IMAP protocols. It has a spell checker and direct support for PGP and GPG for encryption. It has some basic filtering capabilities, and natively supports several email storage protocols. It also has some internationalization support, including Japanese fonts.
It builds on top of these other open source packages: GNOME, libtool, libESMTP, aspell, and gmime. It also can optionally use libgtkhtml for HTML rendering, libkrb5 for GSS-API, and openldap for LDAP functionality. It can optionally be configured to use gpg-error and gpgme libraries.