On 05/08/2013 11:02 AM, Vincent Lefevre wrote:
I suspect that they temporarily changed the Ethernet card without updating their DNS config, as only the last 6 bytes of the IPv6 address changed for this particular mail.
There are lots of ways that IPv6 can get messed up, and people tend not to notice when it happens because relatively few people use IPv6 yet. I can tell you from experience that it's very easy to misconfigure an IPv6 box and end up sending mail out on an IP other than the one intended. I had issues myself recently with my VMs picking up autoconfigured IPv6 addresses and using those instead of the ones that I manually configured. Also it becomes more of an issue with IPv6 because you tend to only configure PTR records for those IPs you actually intend to use (can you imagine how big of a file you'd have if you configured a PTR for every IP in a /64 block?).
Anyways, you should expect to have problems with IPv6 from time to time if you're using it now. You can either accept that these sorts of issues will crop up and do the best you can to resolve them and help others resolve them when they do, or disable IPv6 on your production machines and stick with IPv4 until IPv6 adoption has reached a level where it's more stable.
Peter
