Thunderbird is the default mail client of Xubuntu. It comes with all desired features, including junk filtering, thread display, POP/IMAP support, security features, themes, an extension mechanism, and more. Before you start, make sure you have a working Internet connection (See the section called “Connect to the Internet”).

Launch Thunderbird from Applications->Network->Thunderbird Mail.

After this, the Thunderbird Account Wizard will guide you through the process of entering your account data.