Here you go 
TBPRO=$(find "$HOME"/.thunderbird/ -name "*.default" -print); SMRTD=$(find "$TBPRO"/Mail/ -iname 'smart mailboxes' -print); mkdir -p "$TBPRO"/cut-from-mail; mv "$SMRTD" "$TBPRO"/cut-from-mail/ || echo "Something went wrong. Yell at cscs."