> On Mar 16, 2017, at 2:37 PM, Wietse Venema <wie...@porcupine.org> wrote: > >> When trying to sign up for the list from my regular e-mail address >> (served by my Postfix mail server, on a vhost at Arp Networks) I >> got the following: >> >> <majord...@postfix.org>: host mail.cloud9.net[2604:8d00:0:1::4] >> said: 554 5.7.1 <dougbarton.us>: Helo command rejected: Access denied >> (in reply to RCPT TO command)
Note the use of IPv6 here. Many large providers have chosen to set the bar higher for IPv6 than IPv4. In particular: * PTR records are generally mandatory * SPF and/or DKIM records are often mandatory sadly, while CSA records would have been much more appropriate here, https://tools.ietf.org/html/draft-crocker-csv-csa-00 that idea went nowhere, in the rush to "solve phishing", which of course did not happen with SPF/DKIM/... Anyway, it is quite possible that the problem is that Doug's server has IPv6 connectivity, and he either needs to jump through more hoops... or disable IPv6 in Postfix: inet_protocols = ipv4. -- Viktor.
