SEP 12.1 RU6 has been released & it has a bug related to File repuation lookup alert, make sure you are no longer affected by the same.
File Reputation Lookup Alerts send malformed emails when triggered
Fix ID: 3713171
Symptom: File Reputation Lookup Alert notifications created after the install of Symantec Endpoint Protection Manager 12.1 RU5 sends incomplete emails when triggered and does not include details about why this email was sent.
Solution: File Reputation Lookup Alert notifications are now created correctly and generate the expected email report.
Reference: New fixes in Symantec Endpoint Protection 12.1.6
https://support.symantec.com/en_US/article.TECH230558.html
Upgrading or migrating to Symantec Endpoint Protection 12.1.6 (RU6)
http://www.symantec.com/docs/TECH230601
I would recommend to upgrade to 12.1 RU6.