  <email_alerts>
    <email_to>foo@bar.com</email_to>
    <rule_id>100100</rule_id>
  </email_alerts>

Starting OSSEC HIDS v1.2 (by Daniel B. Cid)...
2007/05/29 08:41:41 ossec-maild(1230): Invalid element in the configuration: 'rule_id'.
2007/05/29 08:41:41 ossec-maild(1202): Configuration error at '/var/ossec/etc/ossec.conf'. Exiting.
2007/05/29 08:41:41 ossec-maild(1202): Configuration error at '/var/ossec/etc/ossec.conf'. Exiting.
ossec-maild: Configuration error. Exiting