====== Postfix ======

===== Postfix support IPv6 =====
  - Postfix version > 2.2
  - Configuration
    - /etc/postfix/main.cf:
      - inet_protocols
        * inet_protocols = ipv4       (DEFAULT: enable IPv4 only)
        * inet_protocols = all        (enable IPv4, and IPv6 if supported)
        * inet_protocols = ipv4, ipv6 (enable both IPv4 and IPv6)
        * inet_protocols = ipv6       (enable IPv6 only)
      - mynetworks
        * IPv6 請用 [] 框起來
        * EX: [::1]/128 [2001:240:587::]/64 [fe80::]/10