Microsoft Alert: Service degradation – Exchange Online – Users are receiving an error when attempting to delist blocked IP addresses at https://sender.office.com – RESOLVED
Issue Reported: 29/07/2021 5:45:00 PM
Microsoft Reference : EX274026
Issue Status: RESOLVED
Issue Description: Users are receiving an error when attempting to delist blocked IP addresses at https://sender.office.com.
Users are seeing the following error message when attempting to delist blocked IP addresses:
“5.1.0 – Unknown address error 550-‘5.7.606 Access denied”
Scope of impact: This issue may impact any user attempting to delist blocked IP addresses at https://sender.office.com.
Final Update – 30/07/2021 09:36:00 AM: A recent configuration change designed to migrate system-generated outbound mail was preventing users from delisting blocked IP addresses at https://sender.office.com. Following Microsoft additional internal validation, have confirmed that impact has been resolved.
