Thanks for using Caldera Forms, we really appreciate it. I’m sorry to hear your emails aren’t working as expected.
Email deliverability is a well-known problem among WordPress form plugins. The ability of Caldera Forms Free and other contact form plugins to send emails is dependent on WordPress’ mailer functionality, which is not terribly reliable across all server configurations.
Personally, I never rely on my WordPress host for sending emails from the form mailer, or the autoresponder processors. The main feature of our paid version of Caldera Forms is to address email deliverability. This is probably the fastest solution to your problem. You can see more information here: https://calderaforms.com/pro/.
Alternatively, you can try the traditional solution to this problem which is to use a third-party service’s API or SMTP servers. We have a tutorial on doing this with Caldera Forms here: https://calderawp.com/doc/improving-the-reliability-of-emails-sent-through-caldera-forms/.
Hope this helps!