It's probably your spam filters. Or, if you use an email filtering service such as SpamArrest, you will never be able to sign up for any site so you might as well give it up.
My spam filter is not that strict in my experience, unless the sender is from some blacklisted address, but you could be right.
But registration pages usually respond with some kind of confirmation when you submit your registration. For example, stating that it sent an email to your email address, containing a link to complete the registration. But this registration page gives no response when you submit your registration (besides generating new captchas).