All of a sudden, customers are not being sent a notification to let them know that their email was not successfully raised as an incident. ie When a customer emails the Service Desk mailbox and puts the word 'update' in the subject, but fails to include the incident number, they should be sent a response saying there was a problem with their request and that they should phone the Service Desk. These emails are now not being sent.
All other (as far as I can tell) notifications are being sent successfully, including when an incident is updated via email. ie. 'Update 123456' will add a note and send an email back to confirm.