Exchange 2016 mail is not leaving, what is the reason?

Question

Mail server

Letters are not sent to some domains
Server returned '400 4.4.7 Message delayed' says
Received: from ZIMEXCH.kronvuz.com (192.168.0.13) by ZIMEXCH.kronvuz.com
(192.168.0.13) with Microsoft SMTP Server (version=TLS1_2 ,
cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1847.3; Fri, 8 May 2020
10:55:28 +0300
Received: from ZIMEXCH.kronvuz.com ([::1]) by ZIMEXCH.kronvuz.com ([::1]) with
mapi id 15.01.1847.003; Fri, 8 May 2020 10:55:28 +0300
From: sale1 [email protected]
To: =?utf-8?B?0JjRgdCw0LXQsiDQkNC90LTRgNC10Lk=?= Subject: =
?utf-8?B?UkU6INCX0LDRj9Cy0LrQsCDQutC+0AL3RgtC10LnYyvd0
?utf-8?Q?.docx?=
Thread -Topic:=?utf- 8 ?B?0JfQsNGP0LLQutCwINC60L7QvdGC0LXQudC90LXRgNGLIDQg0YjRgi4uZG9j?== ?utf -
8?Q?x?= : <[email protected]> the References: <[email protected]> with In-Reply-the To: <[email protected]> the Accept-the Language: ru-RU, en-US the Content -Language: ru-RU X-MS-Has-Attach: yes X-MS-TNEF-Correlator: x-originating-ip: [192.168.0.254] Content-Type: multipart/mixed; boundary="_007_2eddd094ce24436aa32faf105caf4522kronvuzcom_" MIME-Version: 1.0

Answer 1

This data is not enough, but:
telnet mail.dinamika-avia.ru 25
Connecting To mail.kinamika-avia.ru...Could not open connection to the host, on port 25: Connect failed
Perhaps these are the reasons.