KMail is an e-mail client that supports e-mail protocols like POP3 and IMAP. It also has multiple e-mail account support, powerful filters, PGP/GnuPG privacy, and online attachments. Start KMail from the main menu or press Alt+F2 and enter kmail.
Kontact is a personal information management (PIM) tool that combines well-known applications like KMail, KOrganizer, and KAddressBook into a single interface. This lets you have easy access to your e-mail, calendar, address book, and other PIM functionality. To start Kontact, press Alt+F2 and enter kontact. For detailed information about using Kontact, see Section 4.0, Kontact: E-Mailing and Calendaring.