Thunderbird overall considerations:
• Manages both mail and news
• Fast enough both for sending and receiving messages
• Can be expanded through a lot of Plug-Ins (including webmail)
• GUI mono-window/multi-panels approach
• Written in XUL, Geko browsers internal scripting language
• Comes with a RSS feed aggregator
Thunderbird fit those people that need to swith often platform, and whish to mantain always the same interface. Type and license GUI application for Mac OS X, offline.
Freeware, open-source. Languages Monolingual, localized in 32 languages (including Italian).
Throurg the extension “Locale Switcher” Thunderbird becomes capable of multilanguage interface. Platforms Available for Mac OS X, Windows and Linux. Server access Both anonymous and authenticaded server access are available.
Multiple news servers are supported at the same time. Binary support No, Thunderbird is strongly thread and discussions oriented. Filters Flexible built-in filters, with logging capabilities.
Setting up new custom filters is quite simple. Charset/Unicode Charset and Unicode are correctly handled. Thread/Answers Classic expandable tree view.
Several different aggregations and views are also available, by both acting on settings and installing plug-ins. X-Face A Plug-in extension is needed in order to support Faces and X-Faces. | 
