KMail

KMail is a state-of-the-art email client that integrates well with widely used email providers like GMail. It provides many tools and features to maximize your productivity and makes working with large email accounts easy and fast. KMail supports a large variety of email protocols - POP3, IMAP, Microsoft Exchange (EWS) and more.

Features:

• Secure - KMail has secure default settings to protect your privacy, great end-to-end encryption support, and spam detection.
• Powerful - Features include offline support, multiple sender identities, multi-language support, powerful filtering, searching and tagging functionality, mailing list management and very flexible configuration.
• Integrated - Meeting invitations can be easily added as events into KOrganizer, address auto-completion, avatars and crypto preferences are loaded from KAddressBook.
• Standard Compliant - Supports standard mail protocols, push email, server-side filtering and inline OpenPGP, PGP/MIME and S/MIME.