On Thu, Nov 06, 2014 at 09:42:56AM +0100, Heiko Schlittermann wrote:
> They refuse to accept mails from our systems:
>
> SMTP error from remote mail server after initial connection:
> host mx01.kundenserver.de [212.227.17.191]: 554-kundenserver.de (mxeue006) Nemesis ESMTP Service not available
> 554-No SMTP service
> 554 invalid DNS PTR resource record, IP=212.80.235.156
...
> Is there anybody with any good idea?
I'm sure that kundenserver.de uses self-written poor software
that can't handle CNAMEs on PTRs. Proof:
554-kundenserver.de (mxeue005) Nemesis ESMTP Service not available
554-No SMTP service
554 invalid DNS PTR resource record, IP=91.207.115.113
554-kundenserver.de (mxeue003) Nemesis ESMTP Service not available
554-No SMTP service
554 invalid DNS PTR resource record, IP=80.252.139.1
554-kundenserver.de (mxeue005) Nemesis ESMTP Service not available
554-No SMTP service
554 invalid DNS PTR resource record, IP=62.176.2.83
Standart resolver libraries in popular OSes are capable for this
feature since millenium, or even 1996-1997... Nowadays only
self-written resolver could be confused by CNAME. :) I think
this behaviour contradicts common practice, so this is a bug.
--
Eugene Berdnikov
