/usr/ is in ruby-rubymail 1.1.0-2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/all/
/usr/share/rubygems-integration/all/specifications/
/usr/share/rubygems-integration/all/specifications/rmail-1.1.0.gemspec
/usr/share/doc/
/usr/share/doc/ruby-rubymail/
/usr/share/doc/ruby-rubymail/NOTES
/usr/share/doc/ruby-rubymail/README
/usr/share/doc/ruby-rubymail/TODO
/usr/share/doc/ruby-rubymail/copyright
/usr/share/doc/ruby-rubymail/THANKS
/usr/share/doc/ruby-rubymail/guide/
/usr/share/doc/ruby-rubymail/guide/Intro.txt
/usr/share/doc/ruby-rubymail/guide/TableOfContents.txt
/usr/share/doc/ruby-rubymail/guide/MIME.txt
/usr/share/doc/ruby-rubymail/changelog.Debian.gz
/usr/lib/
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/rmail/
/usr/lib/ruby/vendor_ruby/rmail/mailbox.rb
/usr/lib/ruby/vendor_ruby/rmail/version.rb
/usr/lib/ruby/vendor_ruby/rmail/address.rb
/usr/lib/ruby/vendor_ruby/rmail/mailbox/
/usr/lib/ruby/vendor_ruby/rmail/mailbox/mboxreader.rb
/usr/lib/ruby/vendor_ruby/rmail/parser.rb
/usr/lib/ruby/vendor_ruby/rmail/serialize.rb
/usr/lib/ruby/vendor_ruby/rmail/parser/
/usr/lib/ruby/vendor_ruby/rmail/parser/multipart.rb
/usr/lib/ruby/vendor_ruby/rmail/parser/pushbackreader.rb
/usr/lib/ruby/vendor_ruby/rmail/utils.rb
/usr/lib/ruby/vendor_ruby/rmail/message.rb
/usr/lib/ruby/vendor_ruby/rmail/header.rb
/usr/lib/ruby/vendor_ruby/rmail.rb