Activity stream mention on a form is not triggering emails to the mentioned userDescriptionThe Activity stream @ mention functionality on a form is supposed to trigger an email to the user who is mentioned.CauseThe "Activity Stream @Mention Email" notification record is not active on the affected instance. You can verify this from System Notification > Email > Notifications and filter for Name = Activity Stream @Mention Email. In this case users can no't set the "Activity Stream @Mention Email" notification preference to true, causing @ mention email notifications not being created.ResolutionActivate the "Activity Stream @Mention Email" notification record on the affected instance and then set this user preference true for a user, this should resolve the issue.Also, make sure the email field is set on sys_user record, so to create the cmn_notif_device record to send an email notification for @mention functionality.