Email transfer from EUDORA to THUNDERBIRD

Hi,
since Eudora doesn't work anymore, I'm trying Thunderbir, so I transferred the emails with "ImportExport Tool". The emails that are transferred from Eudora to Thunderbird are mixed up with the ones I deleted.I'll give you an example: if I get some propaganda email, I delete them as well as the messages that come from the forums that say: there's a response to your post.In fact, the messages transferred are too many, 2500. And only those messages that I had deleted do not have the subject, but only the title. So I have a lot of confusion of messages.In "ImportExport Tool" I used "Import individual mbox files". What does "Import individual mbox files with sbd structure" mean? I hope I have chosen the right option for importing emails.
Maybe I need to configure "ImportExport Tool"?
Thank you.

Hey FoxAdriano, the issue you're hitting is that Eudora stores deleted emails in the same mailbox file until you compact the mailbox. So when you exported the mbox file, all those "deleted" messages were still physically in there, just marked for deletion.
The fix is to go back to Eudora (if you still can), select each mailbox and do Mailbox > Compact Mailbox. This permanently removes the deleted messages from the file. Then re-export the mbox files and import them into Thunderbird again.
If you can't open Eudora anymore, you can clean them up from the Thunderbird side instead. After importing, sort by subject or sender, select all the ones without a subject line (which are your ghost deleted messages), and delete them. Then compact the folder in Thunderbird (right-click folder > Compact).
Regarding the "sbd structure" option, that's for when you have nested subfolders in Eudora. If you just have flat mailboxes (Inbox, Sent, etc.) then "Import individual mbox files" is the correct choice. The sbd option preserves the subfolder hierarchy if you had one.
Hope that helps, it's a common headache with Eudora migrations.