I've got an issue with an exchange 2013 server.
Any mail being sent to a gmail recipient is rejected due to IPv6 issues, with the following bounceback…
mx.google.com gave this error:
[2002:c30a:e196::c30a:e196] Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication. Please review https://support.google.com/mail/?p=IPv6AuthError for more information . j10si13286393wrc.204 – gsmtp
Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept email from certain senders, or another restriction may be preventing delivery.
The machine doesn't use IPv6 at all, so I opted to add a entry to the registry in the following location, as suggested here…
hkey_local_machine\system\currentcontroset\services\tcpip6\parameters\
I added a Reg_dword titled disabledcomponents with a decimal value of 255 and rebooted the system.
When it came back online, most of the exchange services were stuck in 'starting'.
I removed the reg entry in question and rebooted, and we're back to normal, however I still have the mail delivery issue.
Has anyone come across this before?
pretty much all of the results I can find with this end with this reg key being added and the issue being resolved.
Any help appriciated.
My IPv6 Preference list looks like this…
Precedence Label Prefix
---------- ----- --------------------------------
50 0 ::1/128
40 1 ::/0
35 4 ::ffff:0:0/96
30 2 2002::/16
5 5 2001::/32
3 13 fc00::/7
1 11 fec0::/10
1 12 3ffe::/16
1 3 ::/96
Best Answer
That is a legacy 6to4 address, a deprecated IPv6 transition technology. To solve the problem, you need to disable 6to4 on your server.
From PowerShell as Administrator:
While you're at it, you should also disable other IPv6 transition technologies that are known to cause problems, Teredo and ISATAP: