|Index||-||FAQ - Cart Help Buttons - Cart Settings - 8. Advanced Settings|
This will set the reply-to email address on all order notifications that you receive.
Customer email will allow you to simply hit reply to send your customer an email with additional information about their order.
firstname.lastname@example.org will allow you to easily filter your order emails, and avoid SPF/DMARC problems that may be caused by using the customers email.