Никакой отчет от backup.sh до почты

У меня есть проблема с резервным отчетом в Сервере Ubuntu 16.04. В /usr/local/bin Я имею backup.sh и в течение некоторого времени я не получаю отчет от этого сценария до почты. В /var/mail/nobody Я вижу, что электронные письма пытаются отправить, но существует сообщение:

<admin@mymail.com>: host mymail.com [XXX.XXX.XX.XX] said: 550 5.7.1 Client host rejected: can not find your hostname (in reply to RCPT TO command).

Когда я ввожу hostname -f, Ubuntu возвращает "сервер". В /etc/hostname У меня есть "сервер". Я не могу найти сценарий ответственным за отправку отчета. В backup.sh это не... Возможно, кто-то может направить меня... В main.cf (постфикс) я имею:

    smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = server
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = server.myname.pl, $myhostname, server, localhost.localdomain, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 192.168.14.0/24
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
default_transport = smtp
relay_transport = smtp
inet_protocols = all

Еще одна вещь... Если я даю команду

echo "This is the body of the email" | mail -s "This is the subject line" me@emydomain.pl

В/var/mail/nobody я имею

From MAILER-DAEMON  Thu Mar 28 07:06:26 2019
Return-Path: <>
X-Original-To: root@server.mydomain.pl
Delivered-To: root@server.mydomain.pl
Received: by server (Postfix)
        id 4CE0E10085C; Thu, 28 Mar 2019 07:06:26 +0100 (CET)
Date: Thu, 28 Mar 2019 07:06:26 +0100 (CET)
From: MAILER-DAEMON@server.mydomain.pl (Mail Delivery System)
Subject: Undelivered Mail Returned to Sender
To: root@server.mydomain.pl
Auto-Submitted: auto-replied
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
        boundary="14AB0100854.1553753186/server"
Message-Id: <20190328060626.4CE0E10085C@server>

This is a MIME-encapsulated message.
--14AB0100854.1553753186/server
Content-Description: Notification
Content-Type: text/plain; charset=us-ascii

This is the mail system at host server.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<me@mydomain.pl>: host mydomain.pl[XX.XX.XX.X] said: 550 5.7.1 Client
    host rejected: cannot find your hostname (in reply to RCPT TO command)

--14AB0100854.1553753186/server
Content-Description: Delivery report
Content-Type: message/delivery-status

Reporting-MTA: dns; server
X-Postfix-Queue-ID: 14AB0100854
X-Postfix-Sender: rfc822; root@server.mydomain.pl
Arrival-Date: Thu, 28 Mar 2019 07:06:25 +0100 (CET)

Final-Recipient: rfc822; me@mydomain.pl
Original-Recipient: rfc822;me@mydomain.pl
Action: failed
Status: 5.7.1
Remote-MTA: dns; mydomain.pl
Diagnostic-Code: smtp; 550 5.7.1 Client host rejected: cannot find your
    hostname

--14AB0100854.1553753186/server
Content-Description: Undelivered Message
Content-Type: message/rfc822

Return-Path: <root@server.mydomain.pl>
Received: by server (Postfix, from userid 0)
        id 14AB0100854; Thu, 28 Mar 2019 07:06:26 +0100 (CET)
To: me@mydomain.pl
Subject: This is the subject line
Message-Id: <20190328060626.14AB0100854@server>
Date: Thu, 28 Mar 2019 07:06:25 +0100 (CET)
From: root@server.mydomain.pl (root)

This is the body of the email

--14AB0100854.1553753186/server--