Magento 2 mailing systems, so you may need to check below point:.
Disable the order confirmation email from the Magento Admin and send an email programmatically for website only: Stores > Configuration > Sales > Sales ...
It's possible that the "From" address is wrong. Goto Stores->Configuration-> General->Store Email Addresses and check if "Sales ...
You can use the salesOrderManagementV1 to add a comment to an order email and send an email: POST /V1/orders/{id}/comments POST ...
Previously, email sent from the Admin included incorrect static file paths.
Detailed guide on sending Order Confirmation Email to Customers
When you submit payment information, Magento creates an order and sends an order confirmation to the customer.
Magento Web API · Magento Services · OAuth
POST
Before we begin the exploration of the order lifecycle in Magento 2, make sure that you