Robert Schetterer:
> Hi Andreas , there a "wide" reports that google sometimes fails somehow
> with ipv6, i investigated in this hardly , it simply looks its their
> bug, my best speculation goes in sometimes not working spf ipv6 stuff at
> their site
My domain has no SPF, but it signs all mail with DKIM. Google
decided to reject a single email message at end-of-DATA on 11 Nov
2014 11:55:15 -0500. Minutes later, the same email message passed
(see logfile records below).
Given that TCP worked, I suspect that some DNS lookup failed (PTR,
AAAA, DKIM, etc.). The entire session lasted only a few seconds,
so I suspect they use short timeouts without retries.
Wietse
Nov 11 11:55:15 spike postfix/smtp[22958]: 3jcZv4004YzJrPw:
to=<censored>, relay=aspmx.l.google.com[2607:f8b0:400d:c04::1a]:25,
delay=3.6, delays=0.12/0.01/2.6/0.93, dsn=5.7.1, status=bounced
(host aspmx.l.google.com[2607:f8b0:400d:c04::1a] said: 550-5.7.1
[2604:8d00:189::2] Our system has detected that this message does
not 550-5.7.1 meet IPv6 sending guidelines regarding PTR records
and authentication 550-5.7.1 . Please review 550-5.7.1
https://support.google.com/mail/?p=ipv6_authentication_error for
more 550 5.7.1 information. l17si30149401qaj.81 - gsmtp (in reply
to end of DATA command))
Nov 11 11:58:29 spike postfix/smtp[22980]: 3jcZyr2BpqzJrPw:
to=<censored>, relay=aspmx.l.google.com[2607:f8b0:400d:c04::1a]:25,
delay=1.4, delays=0.11/0.01/0.19/1.1, dsn=2.0.0, status=sent (250
2.0.0 OK 1415725109 k30si37581932qge.88 - gsmtp)
