The simple way is to move all of Local Folders to another drive. Here are the steps: # click help>troubleshootinginformation # scroll to 'profile folder' and click 'open folder # exit thunderbird. you are now in the profile # click the Mail folder # now, highlight Local Folder and COPY to your other drive (do NOT use MOVE) # restart thuunderbird # click 'account settings' # scroll down left side to Local Folders # on the right side of screen is the link to 'Local directory. Click the Browse button and then locate and select the folder on external drive to which you copied the local folder contents # thunderbird will now close and restart to accept the change # once you verify that all is well, you may then delete the Local Folders folder in original profile.