Due to the way Heroku provisions Channels apps no emails are sent by default. Instead Heroku Users will need to follow the below process to add your email address to begin receiving these emails.
It is also possible to add additional email contacts, slack integration or trigger a webhook. This can be done as follows:
1) Log into the https://dashboard.pusher.com
2) Click the dropdown arrow in the top right and select "Limit Notifications"
3) Select the "Notification Type" from the dropdown and add the "Destination"
4) Click "Test" or "Save limit notification" to add this.