/usr/ is in ruby-letter-opener 1.4.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/letter_opener.rb
/usr/lib/ruby/vendor_ruby/letter_opener/
/usr/lib/ruby/vendor_ruby/letter_opener/railtie.rb
/usr/lib/ruby/vendor_ruby/letter_opener/message.html.erb
/usr/lib/ruby/vendor_ruby/letter_opener/delivery_method.rb
/usr/lib/ruby/vendor_ruby/letter_opener/message.rb
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-letter-opener/
/usr/share/doc/ruby-letter-opener/copyright
/usr/share/doc/ruby-letter-opener/README.rdoc
/usr/share/doc/ruby-letter-opener/changelog.gz
/usr/share/doc/ruby-letter-opener/changelog.Debian.gz
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/all/
/usr/share/rubygems-integration/all/specifications/
/usr/share/rubygems-integration/all/specifications/letter_opener-1.4.1.gemspec