I use it. I like it. But... real world can/will bite you in the ass:
Yes, it can. Note this Received header from *your* message:
Received: from trackivity.com (unknown [IPv6:2607:f0b0:0:205::2])
(using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
(No client certificate requested)
by english-breakfast.cloud9.net (Postfix) with ESMTPS id A7ADC33260A
for <postfix-users@postfix.org>; Sat, 12 May 2018 18:45:26 -0400
(EDT)
So, it is good that the mail server handling this list does not use
reject_unknown_client_hostname
<Sigh />
My DNS server is in fact set up correctly for this, and I have requested
that reverse DNS be delegated down to it, but that delegation hasn't
happened yet.
Hardly any traffic that I get is IPv6, and this postfix mailing list
probably accounts for most of it.
Bottom line: no, it's not perfect, but it currently does what I need,
and I can reasonably expect that the rest will improve over time.
So this actually makes an excellent example for the subject of this
thread: "reject_unknown_client_hostname", I use it, I like it, and I
reliably send and receive all the SMTP email that I feel is necessary.
Occasionally there are wobbles but it's never been a crisis. Watch your
logs. Your mileage will vary.
--
- James
