From MozillaWiki

Eudora 8 development evolved into being Eudora OSE. Eudora OSE evolved from an experimental add-on Penelope - a re-imagining and re-implementation of classic Eudora features on top of the Mozilla Thunderbird codebase.

Eudora and OSE no longer exist, nor is there support. Users might instead try Thunderbird.

Trademarks

QUALCOMM and Eudora are registered trademarks of QUALCOMM Incorporated.