Ok, I'll try several options, depending on your skill. If you're comfortable with a bit of windows file explorer, here is the purest and best approach: Here is how i do it: - exit thunderbird on old PC - copy c:\users\<yourid>\appdata\roaming\thunderbird to external media (this assumes you use default installation) - on new PC, install thunderbird and exit - copy the backed-up thunderbird folder to c:\users\<yourid>\appdata\roaming to overwrite the existing thunderbird folder - start thunderbird and everything will be there. If you don't like that option, this may work: - click help>troubleshootinginformation - scroll down to 'profile folder' in left column and click 'open folder' - exit thunderbird - you are now in profile folder, press the back arrow one time to get outside the profile - now, copy that folder to external media - start thunderbird on new PC - click tools>import>import from another thunderbirdinstallation>Choose a profile folder and then locate and select the profile on the external media If your profile is small, this is the least technical: - click tools>export and this will export to a zipped file - on new computer, click tools>import and follow above steps on tools>import>import from a file and then select the profile zip import Let me know how it goes.