Allow overriding topic

core/lib/rules.py

@@ -26,7 +26,14 @@ def rule_matched(rule, message, matched_fields):
 
     notify_message = f"{rule.name} matched on {matched_fields}\n{message}"
     notify_message = notify_message.encode("utf-8", "replace")
-    sendmsg(rule.user, notify_message, title=title, priority=str(rule.priority))
+
+    cast = {
+        "title": title,
+        "priority": str(rule.priority),
+    }
+    if rule.topic is not None:
+        cast["topic"] = rule.topic
+    sendmsg(rule.user, notify_message, **cast)
 
 
 def process_rules(data):