Upstream has recently moved to Git, and the URL i've linked to earlier points still to the old repository. The new one is here: https://code.launchpad.net/~apparmor-dev/apparmor-profiles/+git/apparmor-profiles
And the direct link to the profile is: https://git.launchpad.net/apparmor-profiles/tree/ubuntu/16.10/usr.bin.thunderbird Cheers!
