to_mail

# File actionmailer/lib/action_mailer/part.rb, line 56
    def to_mail(defaults)
      part = TMail::Mail.new

      if @parts.empty?
        part.content_transfer_encoding = transfer_encoding || "quoted-printable"
        case (transfer_encoding || "").downcase
          when "base64" then
            part.body = TMail::Base64.folding_encode(body)
          when "quoted-printable"
            part.body = [Utils.normalize_new_lines(body)].pack("M*")
          else
            part.body = body
        end

        # Always set the content_type after setting the body and or parts!
        # Also don't set filename and name when there is none (like in
        # non-attachment parts)
        if content_disposition == "attachment"
          part.set_content_type(content_type || defaults.content_type, nil,
            squish("charset" => nil, "name" => filename))
          part.set_content_disposition(content_disposition,
            squish("filename" => filename))
        else
          part.set_content_type(content_type || defaults.content_type, nil,
            "charset" => (charset || defaults.charset))      
          part.set_content_disposition(content_disposition) 
        end        
      else
        if String === body
          part = TMail::Mail.new
          part.body = body
          part.set_content_type content_type, nil, { "charset" => charset }
          part.set_content_disposition "inline"
          m.parts << part
        end
          
        @parts.each do |p|
          prt = (TMail::Mail === p ? p : p.to_mail(defaults))
          part.parts << prt
        end
        
        part.set_content_type(content_type, nil, { "charset" => charset }) if content_type =~ /multipart/
      end
    
      part
    end