> What's the good way to disable IPv6 in a debian system? Well i don't know debian system. However i'm using Debian 11. If that is about mail system Postfix, you check this parameter: #+begin_src text inet_protocols = ipv4 #+end_src Sincerely, Linux fan Byung-Hee -- ^고맙습니다 _布德天下_ 감사합니다_^))//