Claws Mail is a GTK+ based, lightweight, and fast email client. Almost all commands are accessible with the keyboard. It also has many features such as multiple accounts, POP3/SMTP/IMAP/NNTP support, OpenSSL, GnuPG, and LDAP support, a plugin system, spell checking, filtering, Actions, spam and virus filters, an address book, internationalization, and much more.
The official Claws Mail Notification plugin already has support for Ubuntu indicators.
Sylpheed-Claws Sylpheed-Claws now has its own, separate Freshmeat.net listing: http://freshmeat.net/projects/sylpheed-claws/
Re: Importing Address book Try this: Open the addressbook: /Tools/Addressbook Select the vCard heading in the window on the left. Then use /File/New vCard, and select your exported vCard.