Hi, @kevinsoma. There is no node.js application server at Netlify after deployment. This means you cannot run any server-side node.js code unless you deploy it as a function. The site you mention has no deployed functions here:
https://app.netlify.com/sites/sparkly-narwhal-930b72/functions
So, as you have no server-side code running at all, I would expect that sending emails would fail. You have not deployed the code that sends the emails in a way that will work.
There is a support guide about this below:
Can the email code be ported to a function? If so, have you done so?