diff --git a/bin/kolab_smtp_access_policy.py b/bin/kolab_smtp_access_policy.py
--- a/bin/kolab_smtp_access_policy.py
+++ b/bin/kolab_smtp_access_policy.py
@@ -1360,15 +1360,18 @@
             if record.recipient == recipient:
                 recipient_found = True
         if not recipient_found:
-            cache_insert(
-                function=function,
-                sender=sender,
-                recipient=recipient,
-                result=result,
-                sasl_username=sasl_username,
-                sasl_sender=sasl_sender,
-                data=data
-            )
+            try:
+                cache_insert(
+                    function=function,
+                    sender=sender,
+                    recipient=recipient,
+                    result=result,
+                    sasl_username=sasl_username,
+                    sasl_sender=sasl_sender,
+                    data=data
+                )
+            except Exception as errmsg:
+                log.error(_("Exception caught: %r") % (errmsg))
 
 
 def defer_if_permit(message, policy_request=None):