in the email behavior, you have is set to redirect to the thankyou.html page. Is it redirecting to that page or just reloading?
the answer to this question will determine where to look for the problem.
if it is just reloading it means there is a problem with the validations on the page.
I see that you have3 different validation server behaviors, you should only have one that is used to perform all of the validations.
If it is directing to the thankyou.html page, it means the email is being sent to the SMTP server, but the SMTP server is refusing to relay the message. you will need to double check the email server settings, the from address and the to address to make sure they are correct for your server.