I have an Amazon EC2 instance. My postfix server sometimes tries to send outbound emails (web form etc) to ipv6 addresses. It fails and the emails go into the queue.

Is there a way to prevent postfix from getting ipv6 mx records, OR allow my instance to connect to ipv6 mail servers?

I don't need to service inbound ipv6 requests.

Is it possible to setup an ipv6 interface with an internal address only (i don't think amazon will give me one).

  • Show log entries and ip addr for your instance. Postfix would not attempt IPv6 unless it thought you already had IPv6 connectivity, and by default, EC2 instances do not. – Michael Hampton Dec 5 '13 at 19:13

You can limit the protocols that Postfix uses with the inet_protocols setting.

inet_protocols = ipv4

would be what you need.

It would be better of course if you do support IPv6 for both inbound and outbound mail. You'll probably use both protocols in production sooner than you think!

  • Excellent. I wish I could support ipv6, but Amazon only supports it through a load balancer at the moment and I dont want to go down that path yet. – Justin Wright Dec 5 '13 at 23:04
  • Understandable choice then – Sander Steffann Dec 6 '13 at 11:05

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