Need app to read Eudora mail (that mailbox file format)
Please download Eudora Mailbox Cleaner, and install it. The app may export mailboxes from Eudora to Thunderbird or Apple Mail with less restrictions or drawbacks than directly importing them in Thunderbird. Additionally you may export them from Thunderbird to Apple Mail.

System requirement: Mac OS X 10.2 - Mac OS X 10.6.8 (with Rosetta installed)

Please check the limitation mentioned on the page thoroughly (especially the 2 GB mailbox limit - and how to circumvent it).