Mozilla Thunderbird email program is based on MPL / GPL / LGPL and uses to operate the engine known from the Firefox browser - Gecko. The application is available in three popular system platforms: Linux, Windows and Mac OS X. The program offers extensive configuration options, allowing adjusting its functionality and appearance according your needs. Attention should be paid to extension system, which like Firefox is able to improve the functionality significantly of the application and change its behaviour / actions.
Mozilla Thunderbird has many interesting features: it supports multiple email accounts, has built-in address book, and also allows you to search emails stored on disk comfortably. The application can sort messages easily - the exchange of e-mails actually resembles a traditional conversation.
The program has a module that protects you from fraudulent messages which aim is to swindling data or passwords - when Thunderbird mail a suspect something, it places a warning.