Nick, I cannot reproduce the fault. I'm on 20.04 and Shotwell version is 0.30.7. 'Send To...' option is enabled from both right-click menu as well as File menu and clicking on it opens up my mail client (in my case Geary but when Geary was not set as default, Thunderbird (default) started and asked to create account). See attached. And when I search caja-sendto in /usr/bin, it is NOT a sym link to nautilus-sendto.
Nick, I cannot reproduce the fault. I'm on 20.04 and Shotwell version is 0.30.7. 'Send To...' option is enabled from both right-click menu as well as File menu and clicking on it opens up my mail client (in my case Geary but when Geary was not set as default, Thunderbird (default) started and asked to create account). See attached. And when I search caja-sendto in /usr/bin, it is NOT a sym link to nautilus-sendto.