On Wed, Jan 15, 2014 at 12:05 PM, Darren Pilgrim <nanog@bitfreak.org> wrote:
host gmail-smtp-in.l.google.com[2607:f8b0:4002:c01::1a] said: 550-5.7.1 [2607:fc50:1000:1f00::2 16] Our system has detected that this 550-5.7.1 message does not meet IPv6 sending guidelines...
I could not reproduce the error during a telnet test. However, I see a substantial number of outgoing 550 5.7.1 rejects that look just like that, mixed in with accepted mail to gmail.com. So it would appear to be transient, but ongoing. And more than a bit troublesome, since it is shown as a 550 reject, and delivery therefore will not be deferred and retried appropriately. Jan 15 15:41:29 [...] Failed "Site gmail.com (2607:f8b0:4002:c01::1a) said after data sent: 550 5.7.1 more information. q48si1281225yhb.127 - gsmtp 550-5.7.1 [2607:f360:0:1f0::40:2f00 12] Our system has detected that this" -- -JH