What format did you store them in?

Thanks for your response. I simply copied the complete Eudora folder to a removable hard disk. I expected to be able to reinstall Eudora after the reload of Windows - I didn't realise that Eudora had changed so much. I therefore have the in.mbx, in.toc, out.mbx, out.toc, etc files. I can read the .mbx files using notepad but of course extracting useful information is very laborious.

The last version of Eudora (Open Source Edition) was really Thunderbird with some variations and extensions. If that couldn't access your Eudora files, it's possible that Thunderbird won't either. One possibility to consider is that the old versions of Eudora (which are "real" or "original" Eudora code) can still be downloaded so you could use one of those to view old emails and/or perhaps export emails into some format that Thunderbird would like. Quite a few people are still using those old Eudora versions for daily email but I wouldn't recommend that as they are getting really old.

Thank you for your help. I downloaded the original version of Eudora and copied the backed-up .mbx and .toc files into Eudora's folder. I found it necessary to rename the 'In' and 'Out' files or Eudora ignored them. I haven't tried to export the emails because my wife (whose machine it is) doesn't want to risk the emails she now has in Thunderbird. Thanks again.

I'm confused about this. I have my Eudora files *.mbx and *.toc files on an external hard drive. What folder do I need to put them in for Thunderbird to pick them up? Do I need to change the extensions for Thunderbird?

Perhaps I wasn't clear. Following Daveh110's advice I downloaded an old version of Eudora which my wife is now using to access her *old* emails. I have not tried to transfer them to Thunderbird.

Again following Daveh110 I would guess you would have to use Eudora to *export* in some suitable format. I haven't needed to investigate this.