email block

I need a solution

My client cannot send email to message lab addresses. We do not send bulk mail and are not listed on any blacklist including Symantec.

Returned emails have a header like this:

Subject: Mail delivery failed : returning message to sender

This message was created automatically by the SMTP relay on


A message that you sent could not be delivered to all of its recipients.

The following address(es) failed:

    SMTP error from remote mail server after RCPT>:

    host []:

    421 Service Temporarily Unavailable: retry timeout exceeded

—— This is a copy of the message, including all the headers. ——

Return-path: <>

Received: from [] (port=40176

                by with esmtp (Exim 4.82_1-5b7a7c0-XX)

                (envelope-from <>)

                id 1gUZwM-00008V-2X

                for <message lab client>; Wed, 05 Dec 2018 11:22:22 -0500

Received: from dmc-Mail2010.dmcdomain.local ([fe80::9c64:df94:9c18:229c]) by  dmc-Mail2010.dmcdomain.local ([fe80::9c64:df94:9c18:229c%10]) with mapi id  14.03.0415.000; Wed, 5 Dec 2018 11:22:22 -0500

X-CTCH-RefID: str=0001.0A020205.5C07FB3E.00DD,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0

From: Abigail Araujo <>

To: <message lab client>

Subject: Test

Thread-Topic: Test

Thread-Index: AdSMtqTriyykCgvwQCKUl+Jmuj+kSQ==

Date: Wed, 5 Dec 2018 16:22:21 +0000

Message-ID: <3C7074C5333CC54287CD83E334D3105709CD65C7@dmc-Mail2010.dmcdomain.local>

Accept-Language: en-US

Content-Language: en-US

X-MS-Has-Attach: yes


x-originating-ip: []

Content-Type: multipart/related;



MIME-Version: 1.0


Content-Type: multipart/alternative;



Content-Type: text/plain; charset=”us-ascii”

Content-Transfer-Encoding: quoted-printable

Our email filter shows a smtp spool like this:

2018-12-09 15:01:18 []:25 Connection timed out
2018-12-09 15:03:25 []:25 Connection timed out
2018-12-09 15:05:33 []:25 Connection timed out
2018-12-09 15:07:40 []:25 Connection timed out
2018-12-09 15:09:47 []:25 Connection timed out
2018-12-09 15:09:47 SMTP error from remote mail server after RCPT TO:<>: host []: 421 Service Temporarily Unavailable
2018-12-09 15:09:47 R=dnslookup T=remote_smtp defer (-44): SMTP error from remote mail server after RCPT TO:<>: host []: 421 Service Temporarily Unavailable

This is my 2nd post and I have emailed the investigation email address twice. So far I have no replies



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