class Mail::AttachmentsList

def initialize(parts_list)
  @parts_list = parts_list
  @content_disposition_type = 'attachment'
  parts_list.map { |p|
    if p.mime_type == 'message/rfc822'
      Mail.new(p.body.encoded).attachments
    elsif p.parts.empty?
      p if p.attachment?
    else
      p.attachments
    end
  }.flatten.compact.each { |a| self << a }
  self
end