The Mozilla-Eudora partnership has debuted Eudora 8.0 beta 1, a new release of the Thunderbird-based email client that incorporates the 'Penelope' add-on. Whereas Eudora is a Thunderbird-based client with extra features added by the Eudora developers, Penelope is an add-on that adds additional functionality to both Eudora and Thunderbird, but is built into the former. According to the development team, most features in Penelope can be accessed when used with Thunderbird, but there are a few that require Eudora in order to work correctly.  In the new release, toolbar icons (and a few other icons) from the original Eudora were moved to Penelope. Also, keyboard shortcuts from the original Eudora were moved to Penelope. You can configure whether these shortcuts in Penelope or the original Thunderbird ones are used in the Penelope panel of the Options/Preferences dialog. Additionally, the menu structure of original Eudora has been copied to a great extent in Penelope.