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Fix Microsoft 365 Error 550 5.7.708: Traffic Not Accepted from This IP
Question details
The user needs to resolve an outbound email delivery failure where messages are rejected by the recipient's email provider due to an IP block.
- Product
- Microsoft 365
- Device & OS
- not provided
- Scenario
- Sending outbound emails from a Microsoft 365 account, especially after an accidental bulk email broadcast or while using a trial tenant.
- Observed behavior
- Outgoing emails bounce back with a Non-Delivery Report (NDR) showing error code 550 5.7.708, stating that traffic is not accepted from the sending IP address.
Verify that you have global or Exchange administrator permissions for your Microsoft 365 tenant, as resolving this server-level IP block requires opening an official support ticket.
Request IP Unblock via Microsoft 365 Admin Center
Submit a support request to Microsoft to investigate the restriction and remove the block on your tenant's IP address.
Error 550 5.7.708 is an intentional restriction placed by Microsoft's automated security systems. It most commonly occurs in Microsoft 365 trial tenants with low reputation or when a sudden spike in bulk email triggers anti-spam protections. Because this is a tenant-level network block, it cannot be fixed by modifying local email client settings.
Navigate to the Microsoft 365 admin center (admin.microsoft.com) and log in using your administrator credentials.
Click on the 'Support' tab in the left-hand navigation menu, then select 'Help & support' to open the virtual assistant pane.
Type 'Error 550 5.7.708' into the search box and press Enter. Review the automated diagnostics provided by the system.
If the automated diagnostic cannot lift the block, click on the headset icon or 'Contact Support' button to open a new support ticket.
Include your public IP address and attach a copy of the Non-Delivery Report (NDR) bounce message in your ticket so the support agent can verify and remove the restriction.
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Frequently Asked Questions
Why did my Microsoft 365 IP get blocked with error 550 5.7.708?
Your IP may be blocked because Microsoft's outbound spam filters detected a sudden spike in bulk emails, or because you are using a new Microsoft 365 trial tenant that has strict outbound traffic limitations to prevent spam abuse.
Can I fix error 550 5.7.708 without contacting Microsoft Support?
No. Because the restriction is enforced at the server level by Microsoft Exchange Online to protect network reputation, an administrator must contact Microsoft Support directly to have the block investigated and lifted.
How long does it take for Microsoft to unblock my IP address?
Once an administrator submits a support ticket with the necessary bounce logs (NDR) and the affected public IP address, it typically takes 24 to 48 hours for the Microsoft support team to review the case and remove the restriction.
