We help IT Professionals succeed at work.
Get Started

IPv6 with Local Exchange sending Bounce Backs

OAC Technology
Last Modified: 2015-12-01
We have a client who is on Comcast with a static IPv4 address and local Exchange.  Comcast has started rolling out IPv6 on everything and they are now receiving bounce backs when sending out (message below).  I've contacted Comcast and they say that they cannot assign a static IPv6 address, therefore we cannot set reverse DNS for IPv6.  I have added their IPv6 address to their SPF record which solved the issue temporarily, but since the IPv6 is dynamic it has changed, then they get bounce backs again.

We have a number of clients behind a hardware firewall, which we disable IPv6 on, and they are not having any problems as they are only communicating with the world on IPv4.

Any idea on a permanent fix to resolve this IPv6 dynamic address issue that inevitably causes bounce backs?

Your message wasn't delivered because of security policies. Microsoft Exchange will not try to redeliver this message for you. Please provide the following diagnostic text to your system administrator.
The following organization rejected your message: mx.google.com.
Sent by Microsoft Exchange Server 2007

Diagnostic information for administrators:
Generating server: SERVER.[xxxx].local
mx.google.com #550-5.7.1 [2601:[xxxx]:c05c] Our system has detected that 550-5.7.1 this message does not meet IPv6 sending guidelines regarding PTR 550-5.7.1 records and authentication. Please review 550-5.7.1 https://support.google.com/mail/?p=ipv6_authentication_error for more 550 5.7.1 information. x75si3472751ioi.11 - gsmtp ##
Watch Question
Top Expert 2015
This problem has been solved!
Unlock 4 Answers and 7 Comments.
See Answers
Why Experts Exchange?

Experts Exchange always has the answer, or at the least points me in the correct direction! It is like having another employee that is extremely experienced.

Jim Murphy
Programmer at Smart IT Solutions

When asked, what has been your best career decision?

Deciding to stick with EE.

Mohamed Asif
Technical Department Head

Being involved with EE helped me to grow personally and professionally.

Carl Webster
CTP, Sr Infrastructure Consultant
Ask ANY Question

Connect with Certified Experts to gain insight and support on specific technology challenges including:

  • Troubleshooting
  • Research
  • Professional Opinions
Did You Know?

We've partnered with two important charities to provide clean water and computer science education to those who need it most. READ MORE