That new mailboxes sidebar in the beta is truly an unholy kludge, it alone sent me running back to v5... For the person who asked (days ago) about migrating from the PC version of Eudora, it should be extremely simple: just drop the mailbox files into the appropriate place in the Eudora folder (which is in the Documents folder) on your Mac. They're just standard mbox files, all plain text. As for moving filters & the address book, you just drop those in place as well and rename them (FILTERS becomes Eudora Filters, NNDBASE becomes Eudora Nicknames...) it's all on Eudora's website and while it's not as easy as drag-and-drop, renaming a handful of files isn't so bad.