Viktor, As you'll see from my original message, I have all of the prerequisites.
The problem persists ... Also, FWIW, I'm not alone with this issue. Another user contacted me privately to say that he's having the same problem. Doug -------------------------------------------- On Thu, 3/16/17, Viktor Dukhovni <postfix-us...@dukhovni.org> wrote: Subject: Re: cloud9 rejecting my mail To: "Postfix users" <postfix-users@postfix.org> Date: Thursday, March 16, 2017, 12:11 PM > 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.
