Hiding dynamic values from front-end

I am following on from the great write up regarding “Getting Default Values from Shortcode Attributes“. The one thing I have been fighting with is hiding this imported value from the front end. When I want to use it for destination-email, it would appear that the built in validator doesn’t like any other field type apart from email* to be used in the “To” address. When I prefix it with hidden it doesn’t validate.

In my case it defies the objective which is having a form that’s pre-populated with an unchangeable email address to a specific recipient. I don’t want the user on the front end see the email, nor be able to change it.

The only way is using css to collapse/hide the input. But that’s inelegant and allows robots scrape the email address.

Is there a solution? Thanks.