Custom error message within wpcf7_before_send_mail

Good day!

I’m using the wpcf7_before_send_mail action to interact with an API before sending the email. If the API returns an error, I want to be able to grab that error, display it as an error and prevent the form from being submitted.

I can’t seem to find what I’m looking for anywhere online (here or even on stackoverflow.com).

I’m asking for help from the plugin author ??