KMail, a mail client tailored to KDE
Rich in features and customization options.
It's a bit complicated to set up when you use it together with all the Kontact suite.
Whether you want a "simple" mail client, or one that’s fully integrated with the all the other communications tools you use, KMail is a great option. As its name suggests, this application is fully compatible with the KDE environment, which offers many advantages.
KMail is a component of the Kontact suite. Although it can be installed independently, it does a great job of working together with the entire suite. It’s somewhat difficult to configure, but nothing that manuals and a quick search can’t solve.
KMail supports POP3, IMAP and SMTP protocols, so you can virtually configure any mail account, and import mail received in other clients. It also has a good filter and a robust search system. KMail gives you the ability to compose a mail in HTML, view a HTML mail in plain text, activate a spell checker in real time, pair it with KWallet for password management, and much more. At a visual and usability level, you can adjust the colors, configure keyboard shortcuts, define how to operate the interface buttons, and more.
Beyond KWallet for managing passwords, KMail is connected via SSL and TLS, making it compatible with S/MIME, PGP/MIME, and OpenPGP. This allows you to encrypt and decrypt messages, as well as sign and verify signatures automatically. As with other e-mail client, KMail also helps you distinguish between messages that you can trust, that are untrustworthy, encrypted etc, via color-coding.
Also, if you have Bogofilter or SpamAssassin installed, KMail adds some additional layers of security to help keep your computer and personal data protected .