The organization that co-ordinates development of the Firefox web browser on Thursday launched a new version of its free Thunderbird e-mail program that adds a range of mail management features.

"Thunderbird 2 has powerful new features and proven security, delivering an improved e-mail experience to users worldwide," Scott MacGregor, lead engineer for Thunderbird at the non-profit Mozilla Foundation, said in a written statement.

The updated e-mail program's new capabilities include a range of features borrowed from blogging, information retrieval and web browsers.

Foremost among the changes is the ability to "tag" messages with unique descriptors or keywords. For example, a user could create and assign the tag "Mother's Day" to a series of e-mails related to planning a surprise party, as well as standard tags such as "important," "personal," and so on. Messages can be assigned an unlimited number of tags and there is no restriction on the number of tags that can be created by a user.

Tagging — a common feature of many blogs and so-called Web 2.0 sites and services — is used to help put information into context and to organize it to make it easier to search for information.

The search function in Thunderbird 2 has also been upgraded, displaying results as the user types in a query, which speeds up searches, Mozilla said. The update also allows users to save previous searches, which can be run again with the click of a mouse, according to Mozilla.

Thunderbird 2 also includes a new navigation mode called message history navigation, enabling people to flip back and forth through their messages, the same way they can with websites when using a web browser.

Another new feature makes it easier for people to retrieve messages from webmail accounts, such as Google's Gmail, by simply entering their user names and passwords into Thunderbird 2. That eliminates the need to go through an elaborate and technical software setup process for retrieving webmail through Thunderbird 2.

Like other Mozilla software, Thunderbird is developed through the open-source movement, allowing a worldwide community of programmers to contribute to the creation of the core program and write their own add-on components that can be used to customize or personalize it.

Existing customizations include the ability to incorporate Voice over Internet Protocol (VoIP) functions and share address books, among other productivity and communications features.

Thunderbird 2 is available as a free download for Windows, Mac and Linux operating systems in more than 30 languages at the Mozilla website.