550 5.7.708
550 5.7.708 Traffic Not Accepted from IP
Microsoft blocked the IP because the traffic resembles high-volume spam or suspicious automated mail.
5.7.708 is common for residential or cloud IP ranges without a sending history. Microsoft requires proof that the mail is legitimate bulk traffic.
Severity
CRITICAL
Provider
Microsoft 365 / Outlook
Reference
Mitigation Portal
Last Reviewed
2025-06-01
How to Fix 550 5.7.708
Follow these steps to resolve this Microsoft 365 / Outlook SMTP error and restore normal delivery.
- ✓Move production mail to a dedicated, properly warmed IP range.
- ✓Provide Microsoft with logs showing opt-in proof and engagement when requesting mitigation.
- ✓Avoid sending from dynamic or consumer broadband space.
- ✓Implement rate controls and authentication that prove you own the domain.
Helpful Resources
More Microsoft 365 / Outlook SMTP Codes
Keep these related troubleshooting guides handy while addressing 550 5.7.708.
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