Hello there jt -Swanson. We have read your message. We try to help you, http://kb.mozillazine.org/Thunderbird_:_FAQs_:_Recover_Deleted_Account The '''Msf.files '''are index files-folders that you reset rebuild. There are no emails included that can be erased. But take a backup of your emails before you going to. And if you have anti virus make one check for your files. Just in case to check if they can be corrupted. Delete the msf.files not the inboxmap. If you just delete the inboxmap you lose all your email. You just can delete one Msf file or just delete all Msf files. For rebuilding re index messages etc you can delete the gloda files. https://support.mozilla.org/en-US/kb/rebuilding-global-database But is this nessaserry? Greetings Firefox volunteer.