Although KMail is a bit feature-heavy, it offers the email superuser a lot of control. KMail is the email component of the KDE Desktop Environment. Fairly easy to use, powerful, and versatile, it is a solid email client for Linux.

Like most KDEs, KMail combines powerful features, useful tools, and a user-friendly interface. It can manage multiple POP and IMAP accounts, as well as mbox and maildir mailboxes. It also allows multiple identities for sent emails.

KMail has powerful and flexible internal mail filters, as well as support for procmail filtering and server-level Sieve scripts. The mail component can filter mail on the server to prevent downloading of huge attachments or spam. You can search through virtual folders that automatically collect all messages that meet certain criteria. These criteria do not include message tags, which you can freely set and apply to messages or conversations.

Most users appreciate KMail's fast and powerful search. The addition of expressions and virtual folders makes email management a breeze. And with IMAP accounts, you can search folders in addition to local searches.