#acl All:read
<<TableOfContents>>
=  Which version of Postfix supports IPv6?  =

Postfix version 2.2 supports IPv4 and IPv6 on the following platforms:

 * AIX 5.1 and later
 * Darwin 7.3 and later
 * FreeBSD 4 and later
 * Linux 2.4 and later
 * NetBSD 1.5 and later
 * OpenBSD 2 and later
 * Solaris 8 and later
 * !Tru64Unix V5.1 and later

For Postfix version 2.1 you should download patch from http://www.ipnet6.org/postfix/ to enable IPv6 support in postfix. There is patch available only for IPv6 and IPv6+TLS together. You should apply the patch to your postfix source code.

=  What are unsupported featureas known limitations of IPv6 support (both version and patch)  =

 * The {{{'smtp_host_lookup'}}} parameter is not effective with IPv6. This is because a different lookup mechanism is used that cannot easily disable the {{{'local'}}} (i.e., non-DNS) lookups. Whether local files or the DNS are used first, is determined by your operating system, e.g. in {{{/etc/nsswitch.conf}}} or {{{/etc/host.conf}}}.
 * The order of IPv6/IPv4 outgoing connection attempts is not yet configurable. First IPv6 is tried before IPv4.
 * No IPv6 open relay checks. Currently there are no blacklists that cover the IPv6 address space.
 * On !Tru64Unix, when using {{{'mynetwork_style = subnet'}}} (or: class), all prefixlengths are set to 128 (host-only) because code cannot determine the prefixlengths automatically.
 * IPv6 does not have class A, B, C, etc. networks. With IPv6 networks, the setting {{{'mynetworks_style = class'}}} has the same
 effect as the setting {{{'mynetworks_style = subnet'}}}


=  How to enable IPv6 on Postfix?  =

It is automatically enabled if you compile postfix the above platforms.

=  How to configure IPv6 on Postfix?  (both patched  and  version 2.2 and later) =

You can configure the following parameter in the {{{ main.cf}}}:

 mynetworks:: IPv6 network ranges are written in the form [ipv6:addr:range]/plen.
 smtp_bind_address6:: Source address for outgoing SMTP connections. The address is specified as a bracketed hex IPv6 address.

= What special configuration can I setup on patched version of postfix? =

 lmtp_bind_address6:: Source address for LMTP client connections. - this is not necessary in mainline 2.2 and later since LMTP uses '''smtp_bind_address6''' also.

= What new parameters can be configured in postfix 2.2 and later? =
 inet_interfaces:: Instead of hard-coding {{{127.0.0.1}}} and {{{::1}}} loopback addresses in {{{master.cf}}}, specify {{{"inet_interfaces = loopback-only"}}} in {{{main.cf}}}. This way you can use the same {{{master.cf}}} file regardless of whether or not Postfix will run on an IPv6-enabled system.
 inet_protocols:: This specifies what protocols Postfix will use when it makes or accepts network connections, and also controls what DNS lookups Postfix will use when it makes network connections.
 {{{
    /etc/postfix/main.cf:
        # You must stop/start Postfix after changing this parameter.
        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)
  }}}
  The '''inet_protocols''' parameter also controls what DNS lookups Postfix will attempt to make when delivering or receiving mail.

= What about the different postfix policy daemon IPv6 support? =

 * The [[PostfixGuide_postfilter|Postfilter]] user customizable policy deamon and system does not support IPv6 yet, but there is plan
 to support in the next version.