create_parts

# File actionmailer/lib/action_mailer/old_api.rb, line 204
    def create_parts
      if String === @body
        @parts.unshift create_inline_part(@body)
      elsif @parts.empty? || @parts.all? { |p| p.content_disposition =~ /^attachment/ }
        lookup_context.find_all(@template, @mailer_name).each do |template|
          self.formats = template.formats
          @parts << create_inline_part(render(:template => template), template.mime_type)
        end

        if @parts.size > 1
          @content_type = "multipart/alternative" if @content_type !~ /^multipart/
        end

        # If this is a multipart e-mail add the mime_version if it is not
        # already set.
        @mime_version ||= "1.0" if !@parts.empty?
      end
    end