Send error 501 5.5.2 RCPT TO syntax error

Error Message : 501 5.5.2 RCPT TO syntax error ['****@****']

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>> Received: from DWKDEPC (115.91.124.35)
>> by ncomservice.co.kr (210.127.211.16) with [Nmail V3.8 20071121(ST)]
>> for <'****@****'> from <****@****>;
>> Wed, 27 Sep 2017 13:53:02 +0900
>> From: =?ks_c_5601-1987?B?sK2067/4?= <****@****>
>> To: =?ks_c_5601-1987?B?J8DMx/a/7Cc=?= <****@****>,
>> =?ks_c_5601-1987?B?J8DMwfa/7ic=?= <****@****>,
>> <'****@****'>
>> Cc: <****@****>,
>> <****@****>,
>> =?ks_c_5601-1987?B?J8equKXHz7TDJw==?= <****@****>,
>> <****@****>
>> References: <001301d33722$253a9b90$6fafd2b0$@ktlc.co.kr>
>> In-Reply-To:
>> Subject: RE: NEW SHIPMENT OF S/ GAGE/ C/ Coavis/ Coavis / ORDER# 90573 - PO GPM1706
>> Date: Wed, 27 Sep 2017 13:53:13 +0900
>> Message-ID: <007901d3374c$8749f6d0$95dde470$@sdaedong.co.kr>
>> MIME-Version: 1.0
>> Content-Type: multipart/related;
>> boundary="----=_NextPart_000_007A_01D33797.F7339AA0"
>> X-Mailer: Microsoft Outlook 14.0
>> Content-Language: ko
>> Thread-Index: AQGA1QCJgQJp+UQKTJEJaFMTfertn6Ns7BvAgAAC1NA=