Send & Receive Issues

How to Fix Microsoft 365 Error 550 5.7.708 When Sending from a CRM

Chanuka Geekiyanage Sep 28, 2026 869 views

Question details

The user needs to resolve email delivery error 550 5.7.708, which blocks traffic from a CRM's sending IP on a new Microsoft 365 subscription, even though Outlook sends messages normally.

How to Troubleshoot Microsoft 365 Error 550 5.7.708 from a CRM

Product: Microsoft 365 / Third-party CRM
Device & OS: not provided
Scenario: Attempting to send automated messages, such as appointment reminders and customer replies, through a third-party CRM connected to a Microsoft 365 email address.
Observed behavior: Emails dispatched via the CRM are rejected with error 550 5.7.708 stating traffic is not accepted from the sending IP, whereas emails sent directly from the Outlook client are delivered successfully.

Before you start

Ensure you have access to your CRM's SMTP configuration settings and your Microsoft 365 global administrator credentials before beginning the troubleshooting process.

Solution 1Recommended

Submit an IP Delisting Request to Microsoft

Use this method to remove the CRM's sending IP address from Microsoft's blocked senders list, which is the most common cause of error 5.7.708.

Error 550 5.7.708 typically indicates that the IP address routing your emails has a poor reputation or is temporarily restricted by Microsoft. This often affects third-party CRMs and new tenant subscriptions.

Identify the Blocked IP Address

Check the bounce-back message (Non-Delivery Report) returned by your CRM to find the specific sending IP address that is being blocked.

Access the Delist Portal

Navigate to the official Microsoft 365 Anti-Spam IP Delist Portal in your web browser.

Submit the Delisting Request

Enter the affected email address and the blocked IP address, complete the CAPTCHA, and click Submit. Follow the verification link sent to your email to confirm the request.

Submit an IP Delisting Request to Microsoft

Propagation Time: It can take up to 24 hours for the IP address to be fully removed from the blocklist across all Microsoft 365 servers after submitting the request.

Solution 2

Verify CRM SMTP Settings and Provider Reputation

Confirm that your CRM is correctly configured and that its shared IP pool is not globally blacklisted.

Solution 3

Escalate to Microsoft or GoDaddy Support

If the IP delisting process does not resolve the block after several days, a support ticket is required to investigate tenant-level restrictions.

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Frequently Asked Questions

What does Microsoft Error 550 5.7.708 mean?

This error means that the IP address attempting to send the email is blocked by Microsoft 365. This usually happens if the IP has a poor reputation, is part of a shared pool flagged for spam, or if the Microsoft 365 tenant is newly created and subject to temporary sending restrictions.

Why can I send emails from Outlook but not from my CRM?

When you send an email directly from Outlook, it is routed authenticated through Microsoft's internal servers. When using a CRM, the emails are routed through the CRM's external servers or third-party IP addresses, which Microsoft's spam filters may flag and block.

How long does the Microsoft IP delisting process take?

Once you submit a request through the Microsoft 365 Anti-Spam IP Delist Portal, it typically takes up to 24 hours for the block to be lifted and for the changes to propagate across all Microsoft servers.

Does purchasing Microsoft 365 through GoDaddy affect email troubleshooting?

Yes, if your Microsoft 365 subscription is managed by GoDaddy, you may need to route certain administrative and support requests through the GoDaddy support dashboard rather than dealing directly with Microsoft support.

Outlook & Email Problems