Microsoft 365 Error Codes

Fix Microsoft 365 NDR Error 5.7.705 (Tenant Sending Threshold Exceeded)

Maira Mehtab Sep 27, 2026 870 views

Question details

Users need to resolve an issue where outgoing emails are blocked due to the tenant exceeding its sending threshold.

Product: Microsoft 365
Device & OS: not provided
Scenario: A Microsoft 365 user or administrator is trying to send outbound emails but is prevented from doing so.
Observed behavior: The system blocks the outgoing email and generates a Non-Delivery Report (NDR) containing the error code 5.7.705.

Before you start

Before contacting support, verify if any accounts within your organization have been compromised or if there is unusual high-volume email activity occurring.

Solution 1Recommended

Secure Tenant Accounts and Contact Microsoft Support

Because this restriction applies at the tenant level to prevent spam, you must secure affected accounts and then work directly with Microsoft Support to remove the block.

The NDR 5.7.705 error is applied automatically by Microsoft when it detects high-volume or malicious email activity originating from a tenant. This is usually the result of a compromised account. Administrators cannot remove this block themselves.

Secure compromised accounts

Identify any potentially compromised accounts. Reset their passwords immediately and enforce Multifactor Authentication (MFA).

Review administrator configurations

Check your Microsoft 365 Admin logs and remove any suspicious, unauthorized email connectors or forwarding rules.

Gather investigation details

Document the information regarding affected senders, password resets, enabled MFA, and any remediation actions you have taken.

Contact Microsoft Support

Go to the Microsoft 365 Admin Center, navigate to 'Help & Support', and open a ticket with Microsoft 365 Support to request the removal of the block.

Support Requirement: You must provide the support team with your investigation details to prove the security risk has been mitigated before they will lift the tenant block.

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Frequently Asked Questions

What causes the Microsoft 365 NDR 5.7.705 error?

This error occurs when a Microsoft 365 tenant exceeds its assigned sending threshold. It is usually triggered by high-volume malicious email activity resulting from compromised accounts within the organization.

Can an administrator remove the 5.7.705 tenant block manually?

No, the NDR 5.7.705 block is applied at the tenant level by Microsoft's automated security systems. You must contact Microsoft 365 Support directly to investigate and lift the restriction.

How can I prevent the 5.7.705 error in the future?

To prevent this issue, enforce strong password policies, require Multifactor Authentication (MFA) for all users, and regularly monitor outgoing mail volumes for unusual activity.

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