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#521 5.7.1 error message

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I sent a message to external user yesterday. And I received #521 5.7.1 error message.

My collegues tried to sent to the recipient, then it was success.


It happened same circustance before. That is why I could not understand this situation.


Now I can send a message to the recipient. I really worry what it happen aganin.


The error message is follow thing.



PLBFSP04 rejected your message to the following e-mail addresses: (<>


PLBFSP04 gave this error:

 PLBFSP04 not accept your message (Your IP address has been registered in SPAM Black IP List.) 

Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept e-mail from certain senders, or another restriction may be preventing delivery.


Diagnostic information for administrators:

 Generating server:

 PLBFSP04 #521 5.7.1 PLBFSP04 not accept your message (Your IP address has been registered in SPAM Black IP List.) ##


Original message headers:

 Received: from ( by ( with Microsoft SMTP Server id  14.1.

225.23; Wed, 11 Jul 2012 23:49:59 +0000

Received: from mail96-co1 (localhost [])       by mail96-co1-

 (Postfix) with ESMTP id 92154DA01DB    for <>; Wed, 11 Jul


 23:49:59 +0000 (UTC)



X-SpamScore: 0

X-BigFish: PS0(z5109hzc89bhzz1202hzzz2fh2a8h668h839hd25hf0ah107ah34h)

Received-SPF: pass (mail96-co1: domain of designates as permitted sender) client-ip=; envelope-;

; ;

Received: from mail96-co1 (localhost.localdomain []) by mail96-co1

 (MessageSwitch) id 1342050595572181_28639; Wed, 11 Jul 2012 23:49:55 +0000


Received: from (unknown [])       by (Postfix) with ESMTP id 8044A44004D     for

 <>; Wed, 11 Jul 2012 23:49:55 +0000 (UTC)

Received: from ( by ( with Microsoft SMTP Server

(TLS) id; Wed, 11 Jul 2012 23:49:55 +0000

Received: from ([]) by ([]) with mapi id 14.16.0175.005; Wed, 11 Jul 2012 23:52:16 +0000

From: =?ks_c_5601-1987?B?vNXB1rvz?= <>

To: "" <>

Subject: =?ks_c_5601-



Thread-Topic: =?ks_c_5601-



Thread-Index: AQHNX8Auj+sS9AkRNEWpIgYL0ohaj5ckwObm

Date: Wed, 11 Jul 2012 23:52:16 +0000



Accept-Language: ko-KR, en-US

Content-Language: ko-KR



Content-Type: multipart/report;




MIME-Version: 1.0





Please, any advice.

All Replies
  • Hi park,


    Thank you for your post.


    As the error messages stated,  your IP address was registered in SPAM Black IP List, that's why the recipient reject your emails. Once the IP address remove from the SPAM Black IP list, then the recipient can receive your emails.


    If this issue once occur, you may contact the recipient and let him to contact the administrator of their organization to check whether your IP address was blocked and then unblocked.


    If there are any questions when using Office 365 in the future, please feel free to post in forum. We are glad to assist you.


    Jolin Qiao

  • Hi park,

    How are things going?

    If there are any quetions, please feel free to post.

    Jolin Qiao

  • Hi Jolin Qiao.

    Thank you for your reply.

    You mentioned that the ip is my IP, but it is not my IP.

    And I have searched this IP, I think this IP is Microsoft's IP.

    I have a question.

    I am using IP router in my company.

    According to you, if my IP is black list, how could my colleagues send messages to recipients?

    I don't understand these situation.

    Please post, I need your help.

    Thank you.

  • Hello Park,

    Below i have provided you with an article , it explains how to know, why you are being blacklisted. Please let us know if this article addresses your issue.

    Mario Novoa
    O365 Technical Support.

  • Hello Park,

    I wanted to know if you are still currently experiencing this issue or if the information i provided to you answered your questions? Please let me know if there is additional questions you may have in regards to this issue.

    Kind Regards,
    Mario Novoa
    O365 Technical Support.