diff --git a/libervia/backend/plugins/plugin_comp_ap_gateway/__init__.py b/libervia/backend/plugins/plugin_comp_ap_gateway/__init__.py
index 58612a72..02e80a13 100644
--- a/libervia/backend/plugins/plugin_comp_ap_gateway/__init__.py
+++ b/libervia/backend/plugins/plugin_comp_ap_gateway/__init__.py
@@ -125,6 +125,10 @@ RE_PERCENT_ENC = re.compile(f"%{HEXA_ENC}")
 RE_ALLOWED_UNQUOTED = re.compile(r"^[a-zA-Z0-9_-]+$")
 
 
+class MissingLocalPartError(Exception):
+    """JID local part is missing"""
+
+
 class APGateway:
     IMPORT_NAME = IMPORT_NAME
     # show data send or received through HTTP, used for debugging
@@ -668,7 +672,7 @@ class APGateway:
             user = self.period_encode(user)
 
         if not user:
-            raise exceptions.InternalError("there should be a user part")
+            raise MissingLocalPartError("there should be a local part")
 
         if node:
             account_elts.extend((node, "---"))
@@ -2094,9 +2098,25 @@ class APGateway:
                 raise exceptions.InternalError(
                     "node or service is missing in mb_data"
                 )
-            target_ap_account = await self.get_ap_account_from_jid_and_node(
-                service, node
-            )
+            try:
+                target_ap_account = await self.get_ap_account_from_jid_and_node(
+                    service, node
+                )
+            except MissingLocalPartError:
+                # we have no local part, this is probably a comment
+                try:
+                    service = jid.JID(mb_data["author_jid"])
+                    if not mb_data["author_jid_verified"]:
+                        raise KeyError
+                except KeyError:
+                    raise exceptions.DataError(
+                        "Can't identify post author. Be sure to use a pubsub service "
+                        "setting the 'publisher' attribute."
+                    )
+                else:
+                    target_ap_account = await self.get_ap_account_from_jid_and_node(
+                        service, node
+                    )
             if self.is_virtual_jid(service):
                 # service is a proxy JID for AP account
                 actor_data = await self.get_ap_actor_data_from_account(target_ap_account)