wp_email_capture_error=3 in pro version

Hi, we have the pro version of your plugin but I’m getting this error.
wp_email_capture_error=3

When I send test emails from the email capture list it works fine but when I fill out the form I get the error.

Can you suggest away to fix this?

https://www.kazzum.org/contact/

Thanks,
Matt

https://www.ads-software.com/extend/plugins/wp-email-capture/