I am having a similar problem. I have been having issues with both of my websites that use this plugin… I am not receiving the customer-submitted forms. I have updated this plugin a while ago, but have not experienced this issue until about three weeks ago. I have discovered that my customers ARE receiving the auto-response email after submitting the form, however, I am NOT RECEIVING their submitted forms in my email.
My web-hosting provider is GoDaddy, and I did configure the SMTP plugin, but to no avail. Am I missing a step?
