The first version of the new software is scheduled for release in the first half of 2007. Qualcomm plans to keep selling current versions of its application until that time.
Created in 1988, Eudora was the most widely used email application during the early days of the internet. The tool pioneered the concept of the always-present folder list pane, and was acquired in 1991 by Qualcomm.
Eudora lost most of its market share to online email services such as Hotmail and Gmail as well as to applications that come bundled free with operating systems, such as Microsoft's Outlook and Apple's Mail.
The switch to a Thunderbird-based application will offer Eudora some key infrastructure improvements, including a cross-platform code base and improved display engine, according to Steve Dorner, vice president of technology at Eudora.
"Making it open source will bring more developers to bear on Eudora than ever before," he said.
The Thunderbird client is developed by the Mozilla Corporation and is available under an open source licence. The application shares most of its code base with the Firefox open source browser.
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