get_message_infos_after_date.rb

  def get_message_infos_after_date(ymail_folder, last_date)
    messages        = []
    oldest_found    = Time.now.to_i
    last_date       = last_date.to_i
    offset          = 0
    while oldest_found > last_date
      hash            = self.request('ListMessages', :fid => ymail_folder.fid, :sortKey => "date", :sortOrder => "down",
                                   :startInfo => offset, :startMid => offset, :numInfo => 100, :numMid => 100)
      found_messages  = hash['result']['messageInfo'].map{|h| Ymail::YmailApi::DataTypes::MessageInfo.make_from_hash(h,ymail_folder)}
      messages.push(*found_messages)

      if found_messages.size < 100
        break
      else
        offset += 100
        oldest_found = messages.last.received_date
      end
    end
    messages.select { |m| m.received_date > last_date }
  end