mwbay

This worked for me.

Edit the pluggables.php file in the includes directory.

remove or comment out the following lines:

$message  = sprintf(__('New user registration on your blog %s:'), get_option('blogname')) . "\r\n\r\n";
	$message .= sprintf(__('Username: %s'), $user_login) . "\r\n\r\n";
	$message .= sprintf(__('E-mail: %s'), $user_email) . "\r\n";

	@wp_mail(get_option('admin_email'), sprintf(__('[%s] New User Registration'), get_option('blogname')), $message);

Registration works as it should, but you won’t get an admin email notification.