Published by exdone
Posted on January 19, 2018
:RFC standard for naming host names
2.1 Host Names and Numbers
The syntax of a legal Internet host name was specified in RFC-952
[DNS:4]. One aspect of host name syntax is hereby changed: the
restriction on the first character is relaxed to allow either a
letter or a digit. Host software MUST support this more liberal
Host software MUST handle host names of up to 63 characters and
SHOULD handle host names of up to 255 characters.
Whenever a user inputs the identity of an Internet host, it SHOULD
be possible to enter either (1) a host domain name or (2) an IP
address in dotted-decimal (“#.#.#.#”) form. The host SHOULD check
the string syntactically for a dotted-decimal number before
looking it up in the Domain Name System.
DOMAIN NAMES – CONCEPTS AND FACILITIES
DOMAIN ADMINISTRATORS OPERATIONS GUIDE
Final-Recipient: rfc822; Original-Recipient: rfc822; Action: failed Status: 5.7.1 Remote-MTA: dns; gmail-smtp-in.l.google.com Diagnostic-Code: smtp; 550-5.7.1 [2607::::] Our system has detected that this message does 550-5.7.1 not meet IPv6 sending guidelines regarding PTR records and 550-5.7.1 authentication. Please review 550-5.7.1 https://support.google.com/mail/?p=IPv6AuthError for more information 550 5.7.1 . j186si6255873qkd.386 - gsmtp
Per the Google information docs. You will need a forward AAAA record along with a SPF and PTR record.