Mail flow problem 451 4.4.0 Primary target ip address responded with 421 4.2.2 Connection dropped.

I have a problem. I cant send emails.

This is message generated by the server after delivery expiration.

Informacje diagnostyczne dla administratorów:

Generowanie serwera: rrcex.RRC

awizo@polkomtel.com.pl
#550 4.4.7 QUEUE.Expired; message expired ##

Oryginalne nagłówki wiadomości:

Received: from rrcex.RRC ([10.0.0.3]) by rrcex.RRC ([10.0.0.3]) with mapi;
 Thu, 24 Apr 2014 11:49:40 +0200
From: Danuta Tulicka <Danuta.Tulicka@rrc.pl>
To: "awizo@polkomtel.com.pl" <awizo@polkomtel.com.pl>
Date: Thu, 24 Apr 2014 11:49:39 +0200
Subject: Awizo dostawy do zam. 4500552772
Thread-Topic: Awizo dostawy do zam. 4500552772
Thread-Index: Ac9fokpz4M4GXXOFSXWmBIqn6h8Nfg==
Message-ID: <BE6B724927534E49B1764D302E9B5781039AD4D77C58@rrcex.RRC>
Accept-Language: pl-PL
Content-Language: pl-PL
X-MS-Has-Attach: yes
X-MS-TNEF-Correlator:
acceptlanguage: pl-PL
Content-Type: multipart/mixed;
	boundary="_006_BE6B724927534E49B1764D302E9B5781039AD4D77C58rrcexRRC_"
MIME-Version: 1.0

After sending email I see error

451 4.4.0 Primary target ip address responded with 421 4.2.2 Connection dropped. Attempted failover to alternate host, but that did not secceed. Either there are no alternate hosts, or deliery failed to all alternate hosts.

This company POLKOMTEL said that they dont have our message in logs.

I tried all basic methods to check connectivity. ping, tracert, telnet their domain, mx servers

please help