see that wdseml part..... that means that they are files created for the sole purpose of allowing the ever so slightly intellectually disabled windows search to find emails. '''They are not emails'''. They do not contains any attachments! Emails are stored in files with the same name as the folder you had them in inside Thunderbird... so the inbox folder in Thunderbird will be the inbox file. To make it easier there is always an MSF file with it. So in this case inbox.msf. Using this add-on https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/ you can import these native MBOX files into your current version of Thunderbird.