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giorgio79
Asked: 2013-08-30 00:08:02 +0800 CST

SPF: softfail (domain of transitioning email does not designate 2a01:4f8:121:2062::2 as permitted sender)

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I am seeing this SPF softfail for emails sent from my server, and I notice that 2a01:4f8:121:2062::2 is an IPV6 address. When I check 2a01:4f8:121:2062::2 it is translated as 0.0.0.2 ipv4, so that ipv6 address seems bogus.

I have a Centos server that does not have ipv6 configured, and I left everything at default.

How can I solve this? Should I disable ipv6 on my server? Is postfix responsible for this? Why postfix sends mail with ipv6 when I never configured it?

As requested (I redacted my valid ipv4 address with XX)

[root@host ~]# ifconfig -a

eth0      Link encap:Ethernet  HWaddr XX:XX:XX:2B:97:82
          inet addr:XX.XXX.XXX.XX  Bcast:XX.XXX.XXX.XX  Mask:255.255.255.255
          inet6 addr: 2a01:4f8:121:2062::2/64 Scope:Global
          inet6 addr: fe80::4261:86ff:fe2b:9782/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:5906959065 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3933424961 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:6766726597523 (6.1 TiB)  TX bytes:1315274953503 (1.1 TiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:34502551 errors:0 dropped:0 overruns:0 frame:0
          TX packets:34502551 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:37797695084 (35.2 GiB)  TX bytes:37797695084 (35.2 GiB)`
centos

1 Answers

  1. Best Answer

    We've established that your server is, in fact, configured for ipv6, and has a perfectly globally-valid address. I think that disposes of the original question.

    If you didn't know you were running v6, you should probably check your ip6tables rules, since it might be participating in all sorts of conversations you neither know about nor want! In case further proof was wanted (I have v6 to my desktop):

    [me@risby ~]$ telnet 2a01:4f8:121:2062::2 110
Trying 2a01:4f8:121:2062::2...
Connected to 2a01:4f8:121:2062::2.
Escape character is '^]'.
+OK Dovecot ready.
quit
+OK Logging out
Connection closed by foreign host.

    If you'd prefer not to be running v6, you can disable it with

    IPV6INIT=no
IPV6_AUTOCONF=no

    in /etc/sysconfig/network-scripts/ifcfg-eth0, though personally I think v6 is the coming wave and you've got a great opportunity to play with it!

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