Is KMail the right email client for the Linux superuser?
While a bit feature-heavy,KMailoffers plenty of control for the email superuser.
KMail is the email component of theKDE Desktop Environment.

The KMail Team
Reasonably easy to use, powerful, and versatile, it is a solidemail client for Linux.
KMail: The Basics
Powerful and flexible mail filters and virtual folders.
Secure and encrypt email using OpenPGP and S/MIME.
Configurable message templates and text expansion to compose replies with often-used text.
The variety of options, menu items, and functions can be a bit overwhelming.
It lacks internal spam filters and tight integration with external tools.
Like most of KDE, KMail combines powerful features, useful tools, and an easy-to-use interface.
It can manage multiplePOPandIMAPaccounts, as well as mbox and maildir mailboxes.
It also allows multiple identities for sent emails.
The email component can filter mail at the server to avoid downloading huge attachments or spam.
you’ve got the option to search through virtual folders that automatically collect all messages matching certain criteria.
Most users appreciate KMail’s fast and powerful search function.
The addition of expressions and virtual folders makes email management a snap.
And with IMAP accounts, you might search folders in addition to searching locally.
KMail supports the display of HTML emails, but can also transform emails into safe and simple text.
The rendering is neat and reasonably secure.
It also colorizes quoted text and sorts messages by threads.
Unwanted mail can be bounced back to the sender, simulating a dead email address.
Also, integration with the calendar lets you easily create to-do items, such as reminders.
KMail also allows you to set up text shortcuts that automatically expand to longer and often-used phrases.
All in all, KMail is a worthy contender to the likes ofMozilla Thunderbirdor web-based interfaces like Gmail.