我发现了一个soloution以及它的原因。问题不在于分隔符，而是因为用户发布了重复的帖子。

Solution:替换

$notify_message .=  preg_replace(\'#[\\s]+#\', \' \',sprintf(    get_comment_meta($comment->comment_ID, \'title\',1))) .\' skrev:\'. "\\r\\n" .       $comment->comment_content . "\\r\\n\\r\\n";

$notify_message =  preg_replace(\'/[\\s]+/\', \' \',sprintf( get_comment_meta($comment->comment_ID, \'title\',1)) .\' skrev:\'. "\\r\\n" . $comment->comment_content . "\\r\\n\\r\\n");

And add following code to function.php in your theme, that will allow same user to make dubplacte post:

    add_filter( \'wp_die_handler\', \'my_wp_die_handler_function\', 9 ); //9 means         you        can unhook the default before it fires

    function my_wp_die_handler_function($function) {
return \'my_skip_dupes_function\'; //use our "die" handler instead (where we won\'t die)
    }

   //check to make sure we\'re only filtering out die requests for the "Duplicate"     error we care about
    function my_skip_dupes_function( $message, $title, $args ) {
if (strpos( $message, \'Duplicate comment detected\' ) === 0 ) { //make sure we only        prevent death on the $dupe check
   remove_filter( \'wp_die_handler\', \'_default_wp_die_handler\' ); //don\'t die
    }
   return; //nothing will happen
    }