If you are using E-junkie purchase buttons to sell your product online, we transmit our IPN requirements to PayPal with every order, which should override any IPN settings manually entered in your PayPal account. The only reason you would need to enter IPN settings manually would be if you are selling from somewhere like eBay where you cannot use the buttons provided by E-junkie to sell the product:
http://www.e-junkie.com/ej/help.ebay.htm
You may have multiple types of thank-you email enabled for your account. We can send a Common Thank-you Email for every order and/or a product-specific email for individual items in the buyer's order. In your E-junkie Seller Admin > Account Preferences screen, you can customize your Common Thank-you Email or just delete the message template there to disable that message. In the settings of each product, you can add a custom Email Message to our standard link presentation, or Enable Templated Email to replace our standard message with a fully custom message from start to end, or Enable Templated Email but leave the Email Message field blank to disable that message. This help page explains more about customizing your thank-you emails:
http://www.e-junkie.com/ej/help.custom.thankyou-email.htm