The solution for me was to use the sysDescr because though the vendor was too lazy to sign up with IANA.org for their own enterprise OID (https://www.iana.org/assignments/enterprise-numbers/enterprise-numbers) and used the Net-SNMP one out of the box, they did at least populate the sysDescr with a unique description. So instead of adding a SNMP OID and a Classifier, I simply added a SNMP Classifier based on the SysDescr. Specifically, Discovery Definitions => CI Classification => SNMP. There (in this case) I created a reference to a BarracudaDevice with a Classificiation Criteria (tab) with sysdescr contains Barracuda Email Security Gateway. NOTE: I first had to create a Baracude Email Security Gateway child class under Network Gear. A dated but still applicable YouTube video on this is - https://www.youtube.com/watch?v=6ULRbpGOSB4 Also if you want this to show up in Changes and Incidents, not just tasks you need to add it to the Principal Class, which can be done by navigating to cmdb_class_info.LIST, create a new Class, click the drop down arrow on Class and set Principal Class to True.
