Rejected email to and other domains due to IPv6 configuration RRS feed

  • Question

  • When I try to send an email to a address (as well as some government addresses and others), I get the following NDR: gave this error:
    [2601:282:702:9100:f8fc:a869:e6c8:4e53] Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication. Please review for more information. x103si10255454ioi.127 - gsmtp 

    Looks like an IPv6 configuration issue, but I can't for the life of me figure it out.  I've changed the policy preference to IPv4, but this only corrected the issue for 48 hours.  I had my ISP put in a PTR record, but they stated they could only do it for IPv4.  They made the change and it only corrected the issue for 48 hours.  I also created a Reverse Lookup in the DNS Manager for the IPv6 configuration.  Still no love.

    What am I missing?  I know that SBS2011 users have been getting these rejections for years, but it seems like there is some kind of workaround that I can't seem to be able to successfully configure.  Short of disabling IPv6 which caused my VPN connection to fail, what else can I do?

    Please help.



    Tuesday, November 24, 2015 11:39 PM


  • Hi,

    As mentioned that:
    1. The sending IP must have a PTR record (i.e., a reverse DNS of the sending IP) and it should match the IP obtained via the forward DNS resolution of the hostname specified in the PTR record. Otherwise, mail will be marked as spam or possibly rejected.
    2. The sending domain should pass either SPF check or DKIM check. Otherwise, mail might be marked as spam.

    Try to configure your system to prefer IPv4 over IPv6:
    DisabledComponents entry which is located at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\

    Detail instruction you may reference:

    >this only corrected the issue for 48 hours.
    Have you confirmed that if the change has been reset? Does it work if re-edit the registry entry? 

    What is the Exchange/Outlook version?

    Best Regards,
    Eve Wang

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    Thursday, November 26, 2015 9:07 AM