This message might be sent out by DS-NOC as an email notification to the email address configured in DS-NOC > Dashboard > Configurations > Notifications > DS-System Notification.
The DS-System got one of the errors displayed in DS-Operator > Setup > Critical Errors Monitoring, "Monitored Errors" tab.
Check the DS-System event log and take the appropriate corrective action if applicable.
To have all DS-System errors/events listed once and their count for a certain period:
In DS-Operator > Logs > event log, set the "from" field to the desired date (e.g. 1 month ago), then click on "Exclude", then on "Select".
DS-System can clear automatically most errors related to invalid files, when such files are detected (e.g. by Autonomic Healing or System admin), they are automatically moved to trash (or just removed if trash is disabled), the corresponding backup set is marked out of sync, so that next scheduled backup will sync the set, and then send again the file detected as corrupted if still available on the backup source.