Unable to recieve messages from certain domains

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  We have just deployed a brand new standalone Exchange 2016 server
  
  Inbound email is working for the most part, but certain domains are getting undeliverable bounce backs to our server
  

  DNS, MX and SPF records are valid

  And the Exchange connectivity analyzer shows all Green inbound SMTP.

  
  this is the bounce back:
  
  Delivery is delayed to these recipients or groups:
   
  user@recipient.com (user@recipient.com)
   
  Subject: test
   
  This message hasn't been delivered yet. Delivery will continue to be attempted.
   
  The server will keep trying to deliver this message for the next 1 days, 19 hours and 57 minutes. You'll be notified if the message can't be delivered by that time.
   
  Diagnostic information for administrators:
   
  Generating server: EXCH01.lan.sender.com
  Receiving server: mail.ldrc.net (205.x.x.x)
   
  user@recipient.com
  Server at mail.ldrc.net (205.x.x.x) returned '400 4.4.7 Message delayed'
  2019-01-03 11:51:18 PM - Server at mail.recipient.com (205.x.x.x) returned '451 4.4.397 Error communicating with target host. -> 421 4.4.2 Connection dropped due to ConnectionAborted'
   
  Original message headers:
   
  Received: from EXCH01.lan.sender.com (172.16.16.205) by
   EXCH01.lan.sender.com (172.16.16.205) with Microsoft SMTP
   Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id
   15.1.1531.3; Thu, 3 Jan 2019 13:59:33 -0600
  Received: from PLWPGEXCH01.lan.sender.com
   ([fe80::e5b2:f5f4:5cb4:f89c]) by EXCH01.lan.sender.com
   ([fe80::e5b2:f5f4:5cb4:f89c%12]) with mapi id 15.01.1531.003; Thu, 3 Jan 2019
   13:59:33 -0600
  From: PERSON <user@sender.com>
  To: "user@recipient.com" <user@recipient.com>
  Subject: test
  Thread-Topic: test
  Thread-Index: AdSjntbthT/vxzIkQZ6PNbY6tJppjQ==
  Date: Thu, 3 Jan 2019 19:59:32 +0000
  Message-ID: <34627cf6d1cd4598b12bd3293c373dfa@sender.com>
  Accept-Language: en-US, en-CA
  Content-Language: en-US
  X-MS-Has-Attach:
  X-MS-TNEF-Correlator:
  x-originating-ip: [64.X.XX]
  Content-Type: multipart/alternative;
          boundary="_000_34627cf6d1cd4598b12bd3293c373dfapowerlandca_"
  MIME-Version: 1.0
  

  Found this in the exchange log, so the connection is being made. But the message isn't being delivered.

  2019-01-07T17:06:29.320Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,0,172.27.2.9:25,205.x.x.x:57459,+,,
  2019-01-07T17:06:29.320Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,1,172.27.2.9:25,205.x.x.x:57459,>,"220 exchange.recipient.com Microsoft ESMTP MAIL Service ready at Mon, 7 Jan 2019 11:06:29 -0600",
  2019-01-07T17:06:29.340Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,2,172.27.2.9:25,205.x.x.x:57459,<,EHLO mx3.sender.com,
  2019-01-07T17:06:29.340Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,3,172.27.2.9:25,205.x.x.x:57459,>,250  exchange.recipient.com Hello [205.x.x.x] SIZE 37748736 PIPELINING DSN ENHANCEDSTATUSCODES STARTTLS X-ANONYMOUSTLS AUTH NTLM X-EXPS GSSAPI NTLM 8BITMIME BINARYMIME CHUNKING XRDST,
  2019-01-07T17:06:29.363Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,4,172.27.2.9:25,205.x.x.x:57459,<,STARTTLS,
  2019-01-07T17:06:29.363Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,5,172.27.2.9:25,205.x.x.x:57459,>,220 2.0.0 SMTP server ready,
  2019-01-07T17:06:29.363Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,6,172.27.2.9:25,205.x.x.x:57459,*, CN=Exchange CN=Exchange 40A5D7371C7F1F9D49DB886B6E61A95E BD729173E66A483F1D77660B3DDD1CB4CDAA09B1 2018-12-27T21:35:32.000Z 2023-12-27T21:35:32.000Z Exchange;exchange.recipient.com,Sending certificate Subject Issuer name Serial number Thumbprint Not before Not after Subject alternate names
  2019-01-07T17:06:29.405Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,7,172.27.2.9:25,205.x.x.x:57459,*,,"TLS protocol SP_PROT_TLS1_2_SERVER negotiation succeeded using bulk encryption algorithm CALG_AES_128 with strength 128 bits, MAC hash algorithm CALG_SHA_256 with strength 256 bits and key exchange algorithm CALG_ECDH_EPHEM with strength 256 bits"
  2019-01-07T17:06:29.435Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,8,172.27.2.9:25,205.x.x.x:57459,<,EHLO mx3.sender.com,
  2019-01-07T17:06:29.435Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,9,172.27.2.9:25,205.x.x.x:57459,*,,Client certificate chain validation status: 'EmptyCertificate'
  2019-01-07T17:06:29.435Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,10,172.27.2.9:25,205.x.x.x:57459,*,,TlsDomainCapabilities='None'; Status='NoRemoteCertificate'
  2019-01-07T17:06:29.435Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,11,172.27.2.9:25,205.x.x.x:57459,>,250  exchange.recipient.com Hello [205.x.x.x] SIZE 37748736 PIPELINING DSN ENHANCEDSTATUSCODES AUTH NTLM LOGIN X-EXPS GSSAPI NTLM 8BITMIME BINARYMIME CHUNKING XRDST,
  2019-01-07T17:06:29.461Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,12,172.27.2.9:25,205.x.x.x:57459,<,MAIL FROM:<user@sender.com> SIZE=95867,
  2019-01-07T17:06:29.461Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,13,172.27.2.9:25,205.x.x.x:57459,*,08D6728F6A32EE2D;2019-01-07T17:06:29.319Z;1,receiving message
  2019-01-07T17:06:29.461Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,14,172.27.2.9:25,205.x.x.x:57459,<,RCPT TO:<user@recipient.com>,
  2019-01-07T17:06:29.461Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,15,172.27.2.9:25,205.x.x.x:57459,>,250 2.1.0 Sender OK,
  2019-01-07T17:06:29.461Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,16,172.27.2.9:25,205.x.x.x:57459,>,250 2.1.5 Recipient OK,
  2019-01-07T17:06:29.485Z,EXCHANGE\Default Frontend EXCHANGE,08D6728F6A32EE2D,17,172.27.2.9:25,205.x.x.x:57459,<,BDAT 93257 LAST,
  

  
  
  

  • Edited by DarkAlman Tuesday, January 8, 2019 3:31 AM

  Monday, January 7, 2019 5:51 PM