Sending Order Confirmations from Multiple EMail addresses

I'm fault finding a OC 2.3.0.2 store. Looking at the mail logs, I can see that order confirmation emails are being sent from two email addresses, sales@mydomain and orders@mydomain. What is confusing me is that I can only see where the admin email address is configured System -> Settings -> Store -> E-Mail. This is currently set to sales@mydomain. Where would the orders@mydomain be configured to also send order confirmations?

Could be added by and extension or a modification to catalog/model/checkout/order.php. Check you extensions and in storage/modification.

As above this doesn't sound like default behaviour so it could be coming from an extension?