This help page explains our thank-you emails in detail, including how to customize or disable them:
Note the difference between product-specific thank-you emails vs. your Common Thank-you Email.
Your Common email gets sent to every buyer, regardless of which or how many items they purchased, so if you want to send buyers just one email per order, this is the message you would want to send. The Common email is always templated, and the [%thankyou_link%] template tag we provide in your default template inserts a link to reach a consolidated thank-you/download page for all items in the buyer's order. You can customize this message template, or just delete it to disable the message, in your Account Preferences. To test this message, you would need to place a free test order as explained in the Testing Your Shopping Cart section here:
Product-specific emails are only sent when that product is purchased; if the buyer orders multiple items which have a product-specific email enabled, they would receive a separate message for each product. Digital products such as downloads normally send a thank-you email by default, providing a link to the buyer's thank-you/download page for just that item alone; in this case, whatever you type in the Email Message field would be ADDED to our standard message and link presentation. However, if you Enable Templated Email for the product, whatever you type in the Email Message field would REPLACE our standard message and link presentation for that product's emails. To disable this message for digital products, you would Enable Templated Email and leave the Email Message field blank. Tangible goods do not send any product-specific email by default, so they only send a message if something is entered in the product's Email Message field. To test this message, you can use Send Free Download Link/Code in your Seller Admin or place a free test order as suggested above.