I'm migrating from an old MacBook to a Dell laptop from Costco. I've installed a .5TB SSD for boot and scratch partitions, and formatted the pre-installed 1TB HDD to Ext4 for longer term storage. Firefox that came with the Ubuntu Mate install seems to use the HDD for Downloads just fine.
Thunderbird on the MacBook was set up for POP mail because I want local storage. It was a newer version than the latest available from the Boutique or Software apps in Ubuntu 20.04.1 and that borked my attempts to import all the Tbird mail and settings in the massive Profile file. I eventually found a Snap for the current Tbird version, banged my head on the import until reading that Snap sets up its own directory for the Profile, and now it's working.
But: Tbird refuses to use my HDD Download folder, offering this friendly and highly detailed message:
In desperation I turned on all Permissions on the HDD and Tbird still pops the error, despite this:
For now I've set Tbird to use the SSD Desktop directory, but that's not viable long term. Anyone have ideas on how to get this working, or would it be better to start over with the latest Tbird from the official mozilla Tbird PPA? I read somewhere that Ubuntu or Mate has shifted to the Evolution app for email, but Tbird meets my needs and I'd rather not delve into a new app.