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?

You can configure the following parameter:

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.

lmtp_bind_address6

Source address for LMTP client connections.