I used the same profile on the same computer dual booting between Windows10 and Linux Mint. My mail was stored on the Windows drive. I normally live in Linux. The other day, while on Windows, I let ThunderBird update. When back on Linux, I could not open TBird as the update forced a separation of profiles. I created an account on Linux and I am receiving new mail while on Linux. BUT... my old mail is stuck on Windows. To read that, I have to reboot to Windows. I made a tar ball of my Windows profile folder and copied it to ~/Thunderbird, and after extracting, named the folder per the profile name created on Linux (yxe2p9be.LinuxProfile). I still can not read my email. Please. How do I copy my historical TBird email from Windows to Linux. Just a side note to Thunderbird folks. Thank you for what you do. I know it it mostly volunteer. I appreciate the quality and the fact it is free. But (you knew there would be a but) you could have provided for this case. You could have provided an import function to allow one to import between forced split profiles. Not just put up a message that says it no longer is supported. You broke my Thunderbird!