Import different profiles

You need to manually bring in the mbox folders (you can just move them) and either manually edit your prefs.js to add the account info (dangerous) or recreate the accounts in the GUI (more work, but safer). The mail is located in your profile folder in a Mail directory. You can move the files and folders around as needed with Thunderbird closed. You may need to delete some of the .msf files if they don't show up right (these are just Thunderbird index files which will be recreated).