I currently use imap with my email hosting provider and has worked well with Thunderbird. However, speeds are getting slower and storage costs have gone up. It is time for me to move non-current emails from my email account to back it up while still accessible. I was wondering if Thunderbird's Local Folders default path (C:\Users\......\AppData\Roaming\Thunderbird\Profiles\......\Mail\Local Folders) can be changed to a google drive folder on D:\ drive. If there are any risks in doing so. Thanks.

I am not going to go into another long process of explaining just how prone to error syncing multi gigabyte files multiple time a minute can be. Suffice to say it is not a good idea to put anything Thunderbird profile related on an remote location, let alone a synced storage thing where corruption is almost guaranteed.

Seconded.

Putting profiles in a shared drive will some day cause you grief.