550 5.7.1 RESOLVER.RST.AuthRequired; authentication required : Urgent Help is Needed RRS feed

  • Question

  • Hello All.

    i am sending the email from domain controller  and some application server  via telnet  and got the below NDR .

    Diagnostic information for administrators:

    Generating server:
    #550 5.7.1 RESOLVER.RST.AuthRequired; authentication required ##

    Original message headers:

    Received: from ( by ( with
     Microsoft SMTP Server id 8.3.389.2; Wed, 15 Jul 2015 04:11:37 +0200
    MIME-Version: 1.0
    Content-Type: text/plain
    Message-ID: <>
    From: <>
    To: Undisclosed recipients:;
    Date: Wed, 15 Jul 2015 04:11:37 +0200

    and i know, the distribution group is restricted and only authenticated users can send the email to the DG.

    From: <> is the internal email address 

    To address which i sent was my internal DG ""

    Due to security reason, we are cannot remove the restriction on DL. 

     if they are using an NON MAPI clients like, telnet, application, thunderbird. we are getting the above NDR

    how to resolve this issue without removing the DG restriction.

    Your fast response is much appreciated 

    • Edited by rush2ramki Thursday, July 16, 2015 6:05 PM
    Thursday, July 16, 2015 6:04 PM


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