Trigger: On Page Exit Intent
Want to capture someone before they leave your website? With this trigger turned on, HollerBox will show your popup before they leave. This is where you will want to include the copy that converts the most and help the person make a quick decision.
When editing your popup, you will want to go into Triggers.
Then in Edit Triggers, turn on On Page Exit Intent.
If that is all you need, then you can close the Edit Triggers, and save / publish the popup.