This is something that can be done on your end in your application. We don’t really store what was purchased or notes, etc. in our system. We only store your order ID and some other relevant information. We don’t send emails for each payment either, so our server is not flagged for spam by other email providers.
Here’s how you would normally accomplish this. Add a “Notes” field to your checkout page. When the user clicks the “Pay” button, create an order record in your database and store the notes value in it. Pass the ID of that record to the atlos.Pay method as orderId.
When you receive a postback notification, use the order ID to fetch the record from your database containing the notes. Then, send a notification email to yourself with the amount and the notes.