Mail notification was not sent to subscribers when updating the knowledge article which is subscribed.Issue A particular user, when subscribed to knowledge article the notifications are not triggered to the user when there is a change updated and published to the knowledge article.CauseWe should define an activity notification preference for receiving the notifications. There is an activity notification preference for the 'revised article' where a subscribable object should be configured.ResolutionCheck the activity notification preference type of the 'an revised article' has a subscribable object or not. The table for checking the notification preference:sn_actsub_atype_notif_pref. By adding the subscribable object to the notification preference resolved the issue.Related LinksCheck the sn_actsub_subobject_stream where the subscribable users for particular knowledge articles and bases are mentioned Check if the UI macro from where the subscribe button which is defined 'kb_view_common_header_toolbar' is customized or not Check the script action 'Activity fanout manager for km' which is used in triggering the notification