The danger with IMAP is that the material stored in your profile may not be complete. But we have to work with what we have to work with. In your old profile there will be a subfolder named ImapMail. Inside that you'll find folders named for email servers and these will represent your P+Q+R+X+Y+Z accounts. If you have several accounts with the same provider, it may not be obvious which folder is which. However browsing them to see what subfolders are mentioned usually helps sort it out. In the new Thunderbird, go to Local Folders and create new subdirectories named for your old accounts. Then close Thunderbird and in your file manager paste in the P+Q folders you have identified from the old profile. Paste them into the new subfolders you created. If all goes well, these old message stores will now appear under Local Folders when you next run Thunderbird. There's no point trying to re-create the ''accounts'' as such, since they can no longer connect to defunct servers or to discontinued email accounts. They don't need, and cannot use, the server connection data that goes with an account.