Looking for a new fully featured mail client? Try out Zimbra Desktop. This open source project is very interesting in that it has many features that people want and looks great. You can use Zimbra Desktop to gather mail from many different accounts including Zimbra Mail, Yahoo! Mail, Gmail, AOL, Outlook or any other work or personal email account using POP or IMAP.
You can download the desktop application from here:
It is easy to install and set up your account.
Zimbra Desktop has calendars, contacts, document management, etc. to provide all the features you want as well.