what is this?
"$comments\n" .;
{ mail($mailto, $subject, $messageproper);}
header( "Location: $thankyouurl" ); exit ;
Make sure $POST contains what you think it does by inserting a var_dump($POST) statement before you build $messageproper.
$messageproper =
"This message was sent from:\n" .
"Name of sender: $name\n" .
"Email of sender: $mail\n" .
"How did I find website : $selected_radio\n" .
"$consent\n" .
"$keyword\n" .
"$comments\n";
mail($mailto, $subject, $messageproper, "From: webmaster@{$_SERVER['SERVER_NAME']}\n");
header("location: $thankyouurl");
exit();
Notice I included a "From:" header in the mail() function which is generally a good idea.
I'm assuming you are executing this code on a genuine domain on the net, and not from a server on your local network. My development server is on my local network and my ISP gets really mad at me when I try to send emails this way. And the receiving domain usually rejects the email as spam because its coming from an IP that belongs to my ISP.
Also, there is a security issue in what you are doing that would basically allow anyone who could access the form to send any content they want to anyone they want from your server....in other words you look like the bad guy. Its called header injection or "mail injection" (google it). Unfortunately, I thought I had this figured out but have pulled all my own contact pages for the time being because I'm not 100% certain they are hacker-proof.