What could cause email notifications from FormsCentral not to be sent when using email receipts?

UPDATE: When the fillers email account is entered as an address outside our work email domain, both the receipt (to an outside account) and the notification (to an internal account) are sent. When the filler's email account is in the same email domain as the noficiation email account, the receipt is being received, but the notification is not. I don't have access to our email servers to see if it is an issue on our end, but I don't see why it would be, as we are receiving the reciepts (I would think if the server was bouncing it based on origin neither would be received), and we also recieve notifications from all other forms.

Still looking for an answer to this. We cannot use email receipts within our own email domain because notifications stop being sent.

Thanks,

Daniel