For reasons best known to you, redirecting readers or site visitors commenting on your blog for the first time to say, a Thank You for Commenting
page would be fascinating.
The code snippet below does the job perfectly well.
function redirect_first_time_commenters( $url, $comment ) {
// get count of user comment
$comment_count = get_comments( array( 'author_email' => $comment->comment_author_email, 'count' => true ) );
// if this is the user first comment, redirect to the "Thank You" Page
if ( 1 == $comment_count ) {
$url = 'http://yoursite.com/thank-you-page/';
}
return $url;
}
add_filter( 'comment_post_redirect', 'redirect_first_time_commenters', 10, 2 );
Change http://yoursite.com/thank-you-page/
to the page URL you wish to redirect a first time commenter to.