I’m experiencing the same as well. I have searched around Google for answers and all I can find was people suggesting to uncheck the “Enable Ajax Submissions. (No page reloads)” option which redirects to a blank page on submit but if you leave it checked, the Submit button just greys out with the page not doing anything.
I have also checked Chrome dev tools and in the network there was a 500 internal server error.
This plugin use to work like a month ago with emails sending and auto responds being received when I was testing. But this was on a live site I tested on.
However, the plugin works fine in local testing environment using Postman SMTP and WP HTML Email plugins.
