Yes, you can send out SNMP traps as Output notifications. Have a check on this 'Alerting with ESA Correlation Rules User Guide for Version 11.2 '. This link is for 11.2 version, but you can find similar document for other versions our community.
At the SNMP server end, you will need the MIB file to parse the Traps sent by ESA.
The MIB file NETWITNESS-MIB.txt is located on the ESA RPM at the following location /usr/share/snmp/mibs. With the MIB file, you will be able to identify the SNMP alerts trigerred from ESA. And, the Trap OID value for ESA is 20.