Xubuntu default mail replacement

Since one of the goals of Xubuntu is providing lightweight and performance on Desktop. It is purposed in this feature to replace default email client Mozilla Thunderbird, with a lighter and more stable email client named Claws Email (http://www.claws-mail.org/)

The motivations for this change purposal is:
- Thunderbird hardware requirements are to heavy for low end machines
- Thunderbird has memory leaks that causes occasionally blocks
- Claws mail is based on the Sylpheed email client one of the most light weight GUI email clients for posix systems making it twice as faster as Thunderbird
- It includes all of the major features of Thunderbird like, SSL over POP3, SMTP, IMAP4rev1 and NNTP protocols, GnuPG support, themes, plugins, and an intuitive UI.

A discussion was started on the following thread of the official Ubuntu forums:

http://www.ubuntuforums.org/showthread.php?t=332781

On the previous thread one of the Project leaders, Colin Leroy, offered in the name of Claws Mail all its support to help Xubuntu developers, by means of cooperating to provide a great user experience to Xubuntu users.