Try this: # create an empty folder in drive D. any name will do. I suggest NOT having any spaces in name # click help>troubleshootinginformation # scroll to 'profiles' and click 'about:profiles' # click the button to create new profile # enter a short name, such as DRIVED # click Next # click 'choose' and select the folder on drive D that you created # click finish #, now, the active profile is in the listed profiles on the screen. click 'open folder' # exit thunderbird - IMPORTANT # you are in the profile for the current profile. select ALL and COPY to clipboard # click to the new empty folder on drive D and PASTE contents there # now, restart thunderbird. you are still in old profile at the moment # click help>troubleshootinginformation and, again, scroll to 'profiles' and click 'about:profiles' # your new profile is listed. set it as default # all should now be okay. thunderbird may want to restart. # when al is well and done, you can then delete the profile from drive C. # I think you've earned a beer and some peanuts to celebrate. NOTE; in future, if you install thunderbird to a new PC, you will save time by backing the appdata\roaming\thunderbird folder NOW. Then, on the reinstall, do it in these steps: - install thunderbird on new pc and start once and exit - replace the existing appdata\roaming\thunderbird folder with the backup - when you now restart thunderbird, it will be using the profile on drive D