Outlook | Web | Outlook on the web for business | Email
Sending, receiving, and organizing email in Outlook on the web for business
hi
thanx for hide my personal information
i send just 1 email from onmicrosoft
i need send email from onmicrosoft
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Mohammed T
0
Reputation points
i need send email from onmicrosoft.com
Your message wasn't delivered. Please try resending the message.
Diagnostic information for administrators:
Generating server: [Moderator note: personal info removed] .prod.outlook.com
[Moderator note: personal info removed] Remote server returned '550 5.7.236 Your message can't be sent because your tenant has exceeded its daily limit for sending email to external recipients from your tenant's onmicrosoft.com domains. For more information see https://aka.ms/EXONdrs.'
Outlook | Web | Outlook on the web for business | Email
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Jayden-P 26,270 Reputation points Microsoft External Staff Moderator2026-07-24T12:07:10.42+00:00 Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.
Hi @Mohammed T
As my research, the error code "550 5.7.236" is thrown when emails are being sent from an onmicrosoft.com domain, and the tenant has reached Microsoft’s external sending limit. The outbound mail sent from default onmicrosoft.com (MOERA) domains is throttled to 100 external messages per 24‑hour rolling window. Once that limit is reached, Exchange Online blocks further messages and returns this error.
Reference: Email non-delivery report (NDR) and SMTP errors in Exchange Online - Exchange | Microsoft Learn
You could try these suggestions:
Wait for the 24‑hour rolling window to reset
Once your tenant falls back below the limit, sending will resume automatically. This usually resolves itself within a few hours depending on when emails were sent.
Using a custom domain
To prevent this issue from recurring, you may want to consider implementing a more permanent solution by shifting your outbound email traffic to a custom domain. Microsoft enforces strict limits on the default onmicrosoft.com domain, capping it at 100 external emails per 24‑hour rolling window, and strongly recommends using a custom domain to avoid throttling and improve overall email deliverability.
You can refer via:
Limiting Onmicrosoft Domain Usage for Sending Emails | Microsoft Community Hub
I hope this helps.
Please feel free to correct me if I misunderstood your request. 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.
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Mohammed T 0 Reputation points
2026-07-24T12:20:51.15+00:00 hi
thanx for hide my personal information
i send just 1 email from onmicrosoft
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Jayden-P 26,270 Reputation points Microsoft External Staff Moderator
2026-07-24T12:41:21.1966667+00:00 The limit is applied at the tenant level, not per message. This means the tenant may have already consumed its allowed external sending quota through other users, shared mailboxes, applications, devices, scripts, or automated workflows before you sent your email.We recommend contacting your IT admin and let them know your situation.
If you are the IT admin, consider open a support ticket via Admin Center. https://learn.microsoft.com/en-us/microsoft-365/admin/get-help-support?view=o365-worldwide#online-support
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Mohammed T 0 Reputation points
2026-07-24T12:48:05.7666667+00:00 i'm the it admin There is only one employee who sent a message. just 1 msg
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Jayden-P 26,270 Reputation points Microsoft External Staff Moderator
2026-07-24T12:54:33.51+00:00 Then I recommend you open a ticket with the support team, they will have internal tools to assist you further.
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Mohammed T 0 Reputation points
2026-07-24T14:45:23.3733333+00:00 Is there any risk associated with the information I concealed? Please tell me.
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Jayden-P 26,270 Reputation points Microsoft External Staff Moderator
2026-07-24T14:57:26.1633333+00:00 If you mean the information from the original question, please rest assured, I have modified it.
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Mohammed T 0 Reputation points
2026-07-24T15:02:57.3133333+00:00 So, there is no need to change anything; thank you.
I would like to clarify that I have two domains. The second domain is working perfectly.
As for the "onmicrosoft" domain, it is intended only for students; we, the administrators, use it solely for sending emails.
The issue is that I want to send an email from the student account to College Board, but the message isn't going through. Thank you.
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Mohammed T 0 Reputation points
2026-07-24T15:03:53.94+00:00 So, there is no need to change anything; thank you. I would like to clarify that I have two domains. The second domain is working perfectly. As for the "onmicrosoft" domain, it is intended only for students; we, the administrators, use it solely for sending emails. The issue is that I want to send an email from the student account to College Board, but the message isn't going through. Thank you. -
Mohammed T 0 Reputation points
2026-07-24T15:05:27.09+00:00 Delivery has failed to these recipients or groups:
[Moderator note: personal info removed] @info.collegeboard.org Your message wasn't delivered. Please try resending the message.
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Jayden-P 26,270 Reputation points Microsoft External Staff Moderator
2026-07-24T15:08:44.77+00:00 Can you provide the non-delivery error code when you send from onmicrosoft.com to info.collegeboard.org? For example, 550 5.7.236.
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Mohammed T 0 Reputation points
2026-07-24T15:12:37.0133333+00:00 Diagnostic information for administrators:
Generating server: .eurprd06.prod.outlook.com
@info.collegeboard.org Remote server returned '550 5.7.236 Your message can't be sent because your tenant has exceeded its daily limit for sending email to external recipients from your tenant's onmicrosoft.com domains. For more information see https://aka.ms/EXONdrs.'
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Jayden-P 26,270 Reputation points Microsoft External Staff Moderator
2026-07-24T15:20:08.1933333+00:00 Thank you for the information.
Since your other domain is able to send external email successfully, this suggests the issue is specific to the onmicrosoft.com domain rather than a general outbound mail issue for the tenant.
The NDR indicates that Microsoft has temporarily blocked external email sent from onmicrosoft.com addresses because the tenant has reached the allowed sending limit for that domain. As a result, emails sent from student accounts using the onmicrosoft.com address may be rejected when sent to external recipients.
I recommend waiting up to 24 hours and then testing again, if the issue continues after that period, you may need to contact Microsoft Support for further assistance.
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Jayden-P 26,270 Reputation points Microsoft External Staff Moderator
2026-07-26T07:17:33.6166667+00:00 I hope you will be able to get it resolved soon.
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