diff --git a/modules/sysadmin_guide/pages/mailman.adoc b/modules/sysadmin_guide/pages/mailman.adoc
index 553e501..8cac006 100644
--- a/modules/sysadmin_guide/pages/mailman.adoc
+++ b/modules/sysadmin_guide/pages/mailman.adoc
@@ -164,3 +164,12 @@ systemctl restart mailmanweb
 
 Most of the logs are located in `/var/log/mailman3/`. In case you are looking for
 postfix logs, they could be found in `/var/log/maillog`.
+
+=== Known error messages
+
+These are the error messages that are common in mailman3 logs:
+
+* `NNTP error for list <listname>`
++
+We don't have NNTP server and this couldn't be disabled in mailman3, so you
+can saw this error in logs, but it could be ignored.