At the end of this tutorial, you will have built an Express App, that exposes an API to send HAL notifications via Mailchain to any EVM-address, ENS name or Unstoppable domain.
You will create on-chain event notifications in HAL Notify, and configure HAL to use your API as a webhook for sending POST requests to. Your app will use the Mailchain SDK to send the notifications and Bearer tokens to authenticate incoming requests.
In most cases, you would add a route to an existing Express App, but for this tutorial, you'll create a new app.
Find the full step-by-step tutorial here: https://docs.mailchain.com/developer/tutorials/integrations/hal-notify-on-chain-notifications/