******@xxxxxx.xxxx.OUTLOOK.COM

Anonymous
2024-07-10T23:46:02+00:00

Delivery has failed to these recipients or groups:

******@xxxxxxxxxxxx.pro
This message couldn't be delivered because the sending email address was not recognized as a valid sender. The most common reason for this error is that the email address is, or was, suspected of sending spam. Contact the organization's email admin for help and give them this error message.

Diagnostic information for administrators:

Generating server: xxxxxxxxxxxxxxxxxx.OUTLOOK.COM

******@xxxxxxxx.pro
Remote server returned '550 5.1.8 Access denied, bad outbound sender AS(42004)'

Original message headers:

Received: from xxxxxxxxxxxx.xxxxxxxxxxxxx.PROD.OUTLOOK.COM

 ([fe80::45bc:6129:9bf8:464e]) by xxxxxxxxxxxxxx.xxxxxxxxxxx0.PROD.OUTLOOK.COM

 ([fe80::45bc:6129:9bf8:464e%4]) with mapi id 15.20.7741.033; Wed, 10 Jul 2024

 23:40:16 +0000

MIME-Version: 1.0

Content-Type: text/plain

Date: Wed, 10 Jul 2024 23:40:16 +0000

Message-ID:

 <DU0Pxxxxxxxxxxxxxxxxxxxxxxxxxxx.EURP250.PROD.OUTLOOK.COM>

Subject: Redefine Success with Precision Estimating
Microsoft 365 and Office | Install, redeem, activate | For business | Other

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

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  1. Reported
    Anonymous
    2024-07-11T00:22:23+00:00

    Dear Erick,

    Good day! Thank you for posting to Microsoft Community. We are happy to assist you.

    Based on your description, you are getting NDR error code 550 5.1.8 when sending emails.

    (For your information security reasons, I masked the private information in your thread to prevent phishing/spoofing risks, please comprehend.)

    This NDR is generated if a user tries to send an email message after their account exceeds the sending limits in Exchange Online.

    If you're a user, follow these steps:

    1. Determine whether your account is compromised.
    2. If your account is compromised, follow the steps in Respond to a compromised email account in Exchange Online.
    3. Ask your administrator to unblock your account so that you can send email.

    For how your IT admin can unblock your account from sending emails:

    The admin can unblock user accounts on the Restricted entities page in the Microsoft 365 Defender portal. After you unblock a user account, all restrictions are usually removed within one hour.

    For more information, see Remove blocked users from the Restricted entities page. 

       *1. In the Microsoft Defender portal at*[*https://security.microsoft.com*](https://security.microsoft.com/ "security.microsoft.com")*, go to****Email & collaboration****&gt;****Review****&gt;****Restricted entities****. Or, to go directly to the****Restricted entities****page, use*[*https://security.microsoft.com/restrictedentities*](https://security.microsoft.com/restrictedentities "security.microsoft.com")*.*
    1. On theRestricted entitiespage, identify the user account to unblock. TheEntityvalue isMailbox*.* Select a column header to sort by that column. To change the list of entities from normal to compact spacing, selectChange list spacing to compact or normal*, and then select* Compact list*.* Use the Searchbox and a corresponding value to find specific users.
    2. Select the user to unblock by selecting the check box for the entity, and then selecting theUnblockaction that appears on the page.
    3. In theUnblock userflyout that opens, read the details about the restricted account on theOverviewpage. Verify that you've gone through the suggestions in theRecommendationssection to confirm that the account isn't compromised or to regain control of the account. When you're finished on theOverviewpage, selectNext*.*
    4. On theUnblock user page*, consider the recommendations and use the links in theMulti-factor authenticationandChange passwordsections toEnable MFAandReset the user's passwordif you haven't done these steps already. Enabling MFA and resetting the password are a good defense against future account compromise.* When you're finished on theUnblock user page*, selectSubmit.*
    5. SelectYesin the warning dialog that opens.

    Note

    Under most circumstances, all restrictions should be removed from the user within one hour. Transient technical issues might cause a longer wait time, but the total wait should be no longer than 24 hours.

    For more detailed information, please refer to this official article: NDR error code 550 5.1.8 (Access denied, bad outbound sender) - Exchange | Microsoft Learn.

    I hope the information helps! If there is any update or I misunderstand you, please feel free to let me know. I will continue to assist you. Your understanding and co-operation are highly appreciated.

    Thanks for your precious time. Have a nice day.

    Sincerely,

    Sherry | Microsoft Community Moderator

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