To send a custom email notification from Stripe after a subscription is cancelled, you can use the Stripe webhooks system.
Steps you would need to take:
- Create a webhook endpoint in your server-side code that listens for Stripe events.
- In the Stripe dashboard, navigate to the Developer > Webhooks section and add your webhook endpoint URL.
- Configure the webhook to listen for the "customer.subscription.deleted" event.
- When the webhook receives this event, it can trigger your custom email notification logic. You point the webhook to your server to a php or python script. Debug the data and send the email to the customer email from the data. You can also integrate Sendgrid, Mailgun, or Mandrill API to actually send the email.
- Test your implementation to ensure that the custom email notification is being sent as expected.
Note: The specifics of this implementation will vary depending on your technology stack and email service provider, but this should give you a general idea of the process.