Message Not Delivered: Email content could not be accessed
The message could not be delivered because an email system involved in transmitting the message had a problem accessing its content.
Try sending the message again in a while as this problem might be temporary or already in the process of being fixed.
If this error persists, contact the email provider for help.
5.6.6: Official Definition
A permanent failure is one which is not likely to be resolved by resending the message in the current form. Some change to the message or the destination must be made for successful delivery.
The message content could not be fetched from a remote system. This may be useful as a permanent or persistent temporary notification.