Pusher is hosted APIs that are flexible, line-separator scalable, and easy to integrate.
For your Pusher account, YAP provides creating email.
Before setup, check that you have granted to YAP the permission for sending notifications to your Pusher account. For this, sign in to Pusher and authorize the permissions requested by YAP.
Users need to provide YAP with an access key and access secret. Please use Connecting to Channels documentation.