added SMTP monitor (#5489)

Co-authored-by: Frank Elsinga <frank@elsinga.de>

server/model/monitor.js

@@ -153,6 +153,7 @@ class Monitor extends BeanModel {
             snmpOid: this.snmpOid,
             jsonPathOperator: this.jsonPathOperator,
             snmpVersion: this.snmpVersion,
+            smtpSecurity: this.smtpSecurity,
             rabbitmqNodes: JSON.parse(this.rabbitmqNodes),
             conditions: JSON.parse(this.conditions),
         };