Solved bug existed due to difference between mailu domain and hostname difference. also refactored during this to find the bug

filter_plugins/domain_tools.py

@@ -0,0 +1,19 @@
+# filter_plugins/domain_tools.py
+# Returns the DNS zone (SLD.TLD) from a hostname.
+# Pure-Python, no external deps; handles simple cases. For exotic TLDs use tldextract (see note).
+from ansible.errors import AnsibleFilterError
+
+def to_zone(hostname: str) -> str:
+    if not isinstance(hostname, str) or not hostname.strip():
+        raise AnsibleFilterError("to_zone: hostname must be a non-empty string")
+    parts = hostname.strip(".").split(".")
+    if len(parts) < 2:
+        raise AnsibleFilterError(f"to_zone: '{hostname}' has no TLD part")
+    # naive default: last two labels -> SLD.TLD
+    return ".".join(parts[-2:])
+
+class FilterModule(object):
+    def filters(self):
+        return {
+            "to_zone": to_zone,
+        }