Google mail requires IPv6 PTR record but Comcast does not supply one
Troubleshooting an email problem, I found this in our logs (after some cleaning):
550-5.7.1 [2601:647:4900:8d00:d830:edff:feb2:8d1f] 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. mp9si75365pbc.76 - gsmtp (in reply to end of DATA command))
I followed the link in that message, which tells the Google requirements. One thing it says is:
Additional guidelines for IPv6
- 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.
- The sending domain should pass either SPF check or DKIM check. Otherwise, mail might be marked as spam.
I have solved the SPF check by adding a TXT record to our DNS, but I can't add the PTR record because only Comcast can do that. The current IPv6 address for our system that sends mail (above) does not have a PTR record.
Is there any chance tha Comcast will put dummy IPv6 PTR records, or am I going to have to wait until the static IPv6 addresses happen?