In order to setup the IPN for your PayPal account, you'll need to log into your PayPal account and go to your Profile.
Some PayPal accounts may have a different view then shown below:
If so, you can see the Instant Payment Notification preferences under "Selling preferences" as shown below:
If your PayPal account looks like below:
Then click on 'More Options'
Go to Instant Payment Notifications and click on update and enable instant payment notification and enter the url shown on your Teapplix; Setup; PayPal page under IPN instructions.
If you take payment from international buyers, you may notice that the addresses may contain special characters and not passed into Teapplix correctly. To fix this, you need to set your Paypal account to take UTF-8 charset:
Login to your PayPal Account
Click on Profile
Click Language Encoding (under Selling Preferences)
Click More Options(button)
Select UTF-8 Encoding and "yes" for using same encoding for IPN