Блок с товарами в шаблон писем.

AddEventHandler("main", "OnBeforeEventSend", "OnBeforeEventSendHandler");

function OnBeforeEventSendHandler($arFields, $arTemplate)
{

   CModule::IncludeModule('iblock');

   $rs = CIBlockElement::GetList(
      array(),
      array(
         'ID' => 6625
      )
   );

   $reklama = '';
   if ($el = $rs->GetNext())
      $reklama = $el['DETAIL_TEXT'];

   $arTemplate["MESSAGE"] = str_replace('</body>', '', $arTemplate["MESSAGE"]);
   $arTemplate["MESSAGE"] = str_replace('</html>', '', $arTemplate["MESSAGE"]);

   $arTemplate["MESSAGE"] .= $reklama . '</body></html>';
}