From ThaiiS Note (Wiki)
SMF
Sources/Post.php
- line 1282 (under // Check the subject and message.)
insert
if(!preg_replace('/[^ก-ฮ]/u','',$_POST['subject'])){
$post_errors[] = 'no_subject';
}
if(!preg_replace('/[^ก-ฮ]/u','',$_POST['message'])){
$post_errors[] = 'no_subject';
}