POP3
IMAP
SMTP
Webmail access
List server options
Aliases
Auto-responders
Forwarding
Shared contacts for the domain
Shared calendars
Shared folders (the shared items must be accessed through the webmail area)

Any email program can be used with the email service including Outlook, Thunderbird, Entourage, and all smart phone email programs. The email setup information link in the support tab of the admin area includes setup instructions for the most common types of email programs.