PayPal - How do I activate Instant Payment Notification (IPN)?
Ec2Biz E-Store System is already have notification variable, so do not need change setting in your profile.
For other system, you can activate Instant Payment Notification (IPN) from your Profile.
Note: Before activating IPN, please read the instructions to ensure that you can support the notification and authentication system.
Heres How:
1. Log in to your PayPal account.
2. Click the Profile subtab.
3. Click the Instant Payment Notification Preferences link in the Selling Preferences column.
4. Click Edit.
5. Click the checkbox and enter the URL to which you would like to receive HTML posts.
6. Click Save.
*** The above information is for reference only, Please seek independent technical advice if found necessary.