Sendmail messages not working, what's the problem?

Question

Debian

The site has moved to a new hosting, the sendmail mail server is installed, messages are not sent , for example, when registering, I receive a server response:

The original message was received at Tue, 29 Dec 2015 09:26:14 +0100
from localhost.localdomain [127.0.0.1]

   ----- The following addresses had permanent fatal errors -----
<ххх@gmail.com>
    (reason: 550-5.7.1 [2001:41d0:1000:c7e::] Our system has detected that this message does)

   ----- Transcript of session follows -----
... while talking to gmail-smtp-in.l.google.com.:

Показать цитирование
<<< 550-5.7.1 [2001:41d0:1000:c7e::] Our system has detected that this message does
<<< 550-5.7.1 not meet IPv6 sending guidelines regarding PTR records and
<<< 550-5.7.1 authentication. Please review
<<< 550-5.7.1  https://support.google.com/mail/?p=ipv6_authentication_error for more
<<< 550 5.7.1 information. sa8si24963813wjb.178 - gsmtp
554 5.0.0 Service unavailable

Статус доставки:

Reporting-MTA: dns; SITE
Received-From-MTA: DNS; localhost.localdomain
Arrival-Date: Tue, 29 Dec 2015 09:26:14 +0100

Final-Recipient: RFC822; [email protected]
Action: failed
Status: 5.7.1
Remote-MTA: DNS; gmail-smtp-in.l.google.com
Diagnostic-Code: SMTP; 550-5.7.1 [2001:41d0:1000:c7e::] Our system has detected that this message does
Last-Attempt-Date: Tue, 29 Dec 2015 09:26:15 +0100

Return-Path: <[email protected]>
Received: from SITE (localhost.localdomain [127.0.0.1])
  by SITE (8.14.4/8.14.4/Debian-4) with ESMTP id tBT8adnC007371
  for <[email protected]>; Tue, 29 Dec 2015 09:36:39 +0100
Received: (from [email protected])
  by SITE (8.14.4/8.14.4/Submit) id tBT8ZdbO007211;
  Tue, 29 Dec 2015 09:35:39 +0100
X-Authentication-Warning: SITE: www-data set sender to [email protected] using -f
To: [email protected]
Subject: =?utf-8?Q?=d0=a0=d0=b5=d1=81=d0=b3=d0=b8=d1=81=d1=82=d1=80=d0=b0=d1=86?=  =?utf-8?Q?=d0=b8=d1=8f_=d0=bd=d0=b0_=d1=81=d0=b0=d0=b9=d1=82=d0=b5_=d0?=  =?utf-8?Q?=ba=d0=bb=d0=b0=d0=bd=d0=be=d0=b2=d1=8b=d1=85_=d1=81=d1=80=d0?=  =?utf-8?Q?=b0=d0=b6=d0=b5=d0=bd=d0=b8=d0=b9_Site.com?=
X-PHP-Originating-Script: 0:Email.php
User-Agent: CodeIgniter
Date: Tue, 29 Dec 2015 09:34:39 +0100
From: "SITE" <[email protected]>
Reply-To: "[email protected]" <[email protected]>
X-Sender: [email protected]
X-Mailer: CodeIgniter
X-Priority: 3 (Normal)
Message-ID: <[email protected]>
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="B_ALT_5682459f47122"

Answer 1

Домен у сервера есть? Пропишите ему в /etc/resolv.conf

Answer 2

Домен размещается на другом хостинге, в его DNS записях изменил IP для А..
Добавил в /etc/resolv.conf domain, не помогло..
Может проблема в том, что я сайт посадил на дополнительный IP и криво его подключил в /etc/network/interfaces ?

# The loopback network interface
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
        address 151.80.230.ххх
        netmask 255.255.255.0
        network 151.80.230.0
        broadcast 151.80.230.ххх
        gateway 151.80.230.ххх

auto eth0:0
iface eth0:0 inet static
    address 51.255.235.ххх
    netmask 255.255.255.ххх
post-up /sbin/ifconfig eth0:0 51.255.235.ххх netmask 255.255.255.ххх broadcast 51.255.235.ххх
pre-down /sbin/ifconfig eth0:0 down

iface eth0 inet6 static
        address 2001:41d0:1000:0c7e::
        netmask 64
        post-up /sbin/ip -family inet6 route add 2001:41d0:1000:0cff:ff:ff:ff:ff dev eth0
        post-up /sbin/ip -family inet6 route add default via 2001:41d0:1000:0cff:ff:ff:ff:ff
        pre-down /sbin/ip -family inet6 route del default via 2001:41d0:1000:0cff:ff:ff:ff:ff
        pre-down /sbin/ip -family inet6 route del 2001:41d0:1000:0cff:ff:ff:ff:ff dev eth0