eMail sending fail

[Prashant Gadekar]

Hi,

We have .NET MVC application and in that we have mail sending functionality.

while sending mail, I am getting below issue for specific customer as for other customers mail is getting delivered.

below is the issue (I have changed the few field for security perspective)

Error: "Remote Server returned '550 5.1.1 RESOLVER.ADR.RecipNotFound; not found'"

Attachment has additional info from email CaCe user got:
"Sending failed to address xxxx@company.xyz
There was no email address You gave. Check recipient address and try again.

Info to admin...

Palvelinta muodostetaan (creating server): ABCDEF.xxx.xx
xxxx@company.xyz

Remote Server returned '550 5.1.1 RESOLVER.ADR.RecipNotFound; not found'

Alkuperäiset viestiotsikot (original message titles):
Received: from ABCDEF.xxx.fi (10.xxx.xx.xx) by ABCDEF.xxx.fi
(10.xxx.xx.xx) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Thu, 18 Jun 2020 14:20:42 +0300
Received: from v-pks-gw-1p.pks.fi (10.204.1.55) by ABCDEF.pks.fi
(10.xxx.xx.xx) with Microsoft SMTP Server id 15.0.1395.4 via Frontend
Transport; Thu, 18 Jun 2020 14:20:42 +0300
Received: from vpksgw1p ([127.0.0.1]) by v-pks-gw-1p.xxx.xx with Microsoft SMTPSVC(8.5.9600.16384);
Thu, 18 Jun 2020 14:20:42 +0300
thread-index: AdZFYoDFLiix8CKgT2qOorZukqPJMg==
Thread-Topic: =?iso-8859-1?Q?CaCe_-_Teht=E4v=E4_:_3224462=2Cxxx=2C?=
=?iso-8859-1?Q?_=2C_www_zzz?=
From: <cccc.user@ccc.cc>
To: <xxxx@company.xyz>
Subject: =?iso-8859-1?Q?CaCe_-_Teht=E4v=E4_:_3224462=2xxx=2C?=
=?iso-8859-1?Q?_=2C_www_zzz?=
Date: Thu, 18 Jun 2020 14:20:42 +0300
Message-ID: <BE78B639F57C47D980992818BA4FF897@xxx.xx>
MIME-Version: 1.0
Content-Type: text/plain
Content-Transfer-Encoding: quoted-printable
X-Mailer: Microsoft CDO for Windows 2000
Content-Class: urn:content-classes:message
Importance: normal
Priority: normal
X-MimeOLE: Produced By Microsoft MimeOLE V6.3.9600.19724
Return-Path: cccc.user@ccc.cc
X-OriginalArrivalTime: 18 Jun 2020 11:20:42.0359 (UTC) FILETIME=[80C62870:01D64562]

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