After upgrading Messaging Gateway (SMG) from 10.7.3 to 10.7.4 SNMP queries for mail server statistics no longer operated as expected and returned the error:
snmpwalk -v2c -m all -c public HOSTNAME .184.108.40.206.4.1.3220.127.116.11.2.1.1
No such instance currently exists at this OID
When upgrading from 10.7.3 to 10.7.4, the files needed to return MTA statistics to SNMP were not properly upgraded.
This issue has been addressed with the SMG 10.7.5 release.
Following the upgrade to SMG 10.7.5 the MTA statistics will be returned by SNMP as expected.