# File lib/vmail/imap_client.rb, line 292
    def format_flags(flags)
      # other flags like "Old" should be hidden here
      flags = flags.map {|flag| FLAGMAP[flag] || flag}
      flags.delete("Old")
      if flags.delete(:Seen).nil?
        flags << '+' # unread
      end
      flags.join('')
    end