Mozilla Firefox has the key
browser.cache.parent_directory for this but in Thunderbird I couldn't find it.
Did you try adding the option yourself?
After you open the config editor (
In the context menu, choose
You will be asked to enter the preference name, put in
It will create a directory called
P.S. It is
In Version 24 of Thunderbird you get to the configuration menu by: ...Tools > options > Advanced > General > Config Editor Then everything is the same as above.