EMAIL SERVICES
Gmail is a free email service from Google
Google provides a page that describes how to set up various email clients to retrieve email
EMAIL CLIENTS
Evolution is a Linux email client that includes support for connecting to Microsoft Exchange servers -- including the use of calendar appointments.
IMAP configuration:
LinuxLoop provides a good description of how to configure Evolution to use IMAP for retrieving Google emails
POP configuration:
Ubuntu's Community Help Wiki provides a good description of how to configure Evolution to use POP for retrieving Google emails