On Sun, Mar 24, 2019 at 09:00:24PM +0000, Nick Howitt wrote:
[ Please avoid pasting "non-breaking space" characters into
your email. It is tedious to have to convert these to ASCII. ]
> The header is below (x headers and DKIM removed):
>
> Return-Path: <g...@hz.gov.cn>
> Received: from hz.cn (unknown [220.191.208.116])
> by howitts.co.uk (Postfix) with ESMTP id 6614E401361E
> for <usern...@howitts.co.uk>; Sun, 24 Mar 2019 10:09:30 +0000 (GMT)
The "unknown" means that either:
1. The IP did not resolve to a PTR (name) record
2. The name did not resolve back to the same IP
In case 2. the IP could have had a reverse name.
> Mar 24 10:09:30 server postfix/smtpd[8102]: warning: hostname
> mail.hz.cn does not resolve to address 220.191.208.116
> Mar 24 10:09:30 server postfix/smtpd[8102]: connect from
> unknown[220.191.208.116]
This is case 2.
> Have I misunderstood something or is something else at play?
Inattention to detail, and/or unfamiliarity of the meaning of
"unknown" in the Received header.
--
Viktor.
