To test with PayPal sandbox, you go to https://www.sandbox.paypal.com/ and register your own sandbox account, then you create a sandbox account for merchant and an account for buyer.

In the PayPal plugin configuration, you enter merchant sandbox account and set environment to "Sandbox".

When you purchase for gift card in front-end, you pay with the buyer sandbox account you have created, if everything goes well you will receive emails.

WE LOVE JOOMLA

Joomwalker is not affiliated with or endorsed by the Joomla Project or Open Source Matters.
The Joomla name and logo are used under a limited license granted by Open Source Matters the trademark holder in the United States and other countries.