I have struggled pasting screenshots into Thunderbird for too long. This is how I made it work:
- Installl CopyQ because nothing else worked for me: https://github.com/hluk/CopyQ
- Here's your scrot command:
scrot -s -e 'mv $f /tmp/ && copyq write image/png - < /tmp/$f && copyq select 0'
2.5. Here's your i3wm bindsym scrot command:bindsym --release $mod+Print exec scrot -s -e 'mv $f /tmp/ && copyq write image/png - < /tmp/$f && copyq select 0'
Have fun