Erroneous "Remote server returned '550 5.7.233" NDR

Robert Moss 10 Reputation points

An employee received a "Remote server returned '550 5.7.233 - Your message can't be sent because your tenant has exceeded its daily limit for sending email to external recipients (tenant external recipient rate limit)." NDR.

When I check the Tenant Outbound External Recipients graph in Exchange Admin Center I see that our rate has barely reached 300 emails in any given 24 hour period. I have checked 24 hours, 7 days and 30 days. Nothing even close to a thousand, let alone the 17,123 limit.

Does anyone have any idea how this 'hugely' false alarm level has been reached?

Thank you.

Rob M.

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2 answers

  1. Mike Valdez 0 Reputation points

    We are also having this message Erroneously pop up this morning when trying to send emails to a new customer that we were already corresponding with. I checked and we are nowhere near the limit of sending emails. This message is defaulting as this because of something else/new bug?

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  2. Hin-V 15,490 Reputation points • Microsoft External Staff • Moderator

    Hi @Robert Moss

    Thank you for sharing your concern. 

    Based on my research, this behavior can occur when the effective limit applied to the tenant is lower than expected, rather than this being a false alert. While the Tenant External Recipient Rate Limit (TERRL) is normally calculated based on the number of licensed users and counts the total number of external recipients, Exchange Online can enforce significantly lower limits under certain conditions. 

    For example, this can occur when emails are sent using the *.onmicrosoft.com domain, or when the tenant is in a trial state or temporarily lacks valid licenses. In these scenarios, the limit may be reduced to approximately 100 external recipients per 24 hours, independent of the standard TERRL calculation. 

    Could you please confirm whether emails are being sent from an *.onmicrosoft.com address, or if there has been any recent licensing gap or trial usage on the tenant? 

    If so, this would explain why the EAC report shows relatively low usage (for example, around 300 recipients), while outbound sending is still being blocked, since the effective limit enforced in these cases is much lower. 

    You can refer more via: 

    Introducing Exchange Online Tenant Outbound Email Limits | Microsoft Community Hub 

    Remote server returned '550 5.7.233 - Your message can't be sent because your tenant has exceeded i… 

    I hope this helps. 

    If you have any additional concerns, feel free to comment below. I would be more than happy to assist. 

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.   

    1. Robert Moss 10 Reputation points

      Good afternoon Hin-V. In answer to your question, we don't ever use the .onmicrosoft.com domain for email. We have had no interruption in subscription licensing and no trials.

    2. Mike Valdez 0 Reputation points

      This is our situation as well.

    3. Hin-V 15,490 Reputation points • Microsoft External Staff • Moderator

      Hi @Robert Moss and @Mike Valdez

      Thank you for your updates.

      It is possible for the actual recipient count used for enforcement to be significantly higher than what is visible in the report, especially if large groups or automated sending are involved.

      To help narrow down the issue, please check the following:

      Run a message trace to identify emails with unusually high recipient counts.

      Verify whether any distribution lists with external members are being used.

      Check if any applications, connectors, or service accounts are sending emails externally.

      If the source still cannot be identified, I recommend opening a support case with Microsoft Support . This will allow their team to review backend recipient counts and determine exactly what contributed to the limit. A support engineer can also perform a deeper investigation and validate the tenant configuration as needed.

      Reference: Get support - Microsoft 365 admin | Microsoft Learn 

      Note: To create a support ticket, you need to have Microsoft 365 admin privileges and if you aren’t admin of your organization, please contact the admin of creating a new ticket. 

      Since this is a user‑to‑user support forum and we are not Microsoft Support. Moderators participating here do not have access to backend systems, nor can we directly intervene in Microsoft product functionality. Our role is limited to providing technical guidance and sharing best‑practice recommendations based on reported issues, requests, and scenarios. For that reason, the most efficient solution would be to contact Microsoft’s support team directly.

      Please feel free to share any findings from Microsoft Support. Any update would be appreciated.

      Warm regards,

    4. Hin-V 15,490 Reputation points • Microsoft External Staff • Moderator

      Hi @Robert Moss
      Good day, I hope you’re doing well. I just wanted to follow up and check if there are any updates from your side.

      Have you raised a ticket or received any updates from the Microsoft support team yet?

      If you have any questions, please feel free to reach out. I’ll be happy to assist further.

      Looking forward to your update.

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