log event when there's no dmarc result

app/email_utils.py

@@ -1451,7 +1451,9 @@ def get_dmarc_status(msg: Message) -> Optional[DmarcCheckResult]:
         sep = spam_entries[entry_pos].find("(")
         if sep > -1:
             spam_entries[entry_pos] = spam_entries[entry_pos][:sep]
+
     for header_value, dmarc_result in DmarcCheckResult.get_string_dict().items():
         if header_value in spam_entries:
             return dmarc_result
+
     return None

email_handler.py

@@ -547,6 +547,10 @@ def apply_dmarc_policy(
         newrelic.agent.record_custom_event(
             "Custom/dmarc_check", {"result": dmarc_result.name}
         )
+    else:
+        newrelic.agent.record_custom_event(
+            "Custom/dmarc_check", {"result": "N/A"}
+        )
 
     if not DMARC_CHECK_ENABLED or not dmarc_result:
         return None