diff --git a/admin_manual/groupware/calendar.rst b/admin_manual/groupware/calendar.rst
index ea96c20bde2..33c48ad9bd4 100644
--- a/admin_manual/groupware/calendar.rst
+++ b/admin_manual/groupware/calendar.rst
@@ -39,6 +39,12 @@ See :doc:`../configuration_server/email_configuration`.
 
 You must also make sure the "Send invitations to attendees" setting is activated in the admin setting groupware section for the emails to be sent.
 
+Administrators can disable the sending of invitations to external participants with the following command::
+
+ sudo -E -u www-data php occ config:app:set dav caldav_external_attendees_disabled --value yes
+
+This prevents invitations from being sent to attendees outside the instance and hides external contacts from the invitee search.
+
 Birthday calendar
 -----------------
 Contacts that have a birthday date filled are automatically added as events to a special Birthday calendar.