error message received "outlook.com couldn't confirm that your message was sent from a trusted location.'

Hi @afinsw treasurer

The 550 5.7.23 error means that Outlook.com could not verify the email server used by the sending Exchange account. The issue is therefore on the sender’s side, rather than with the receiving @outlook.com account. 

As a first step, please sign in to Outlook on the web using the affected Exchange account, or use another email, and send it directly to the Outlook.com address. Please avoid using an email application, scanner, website, forwarding service, or other third-party system for this test. 

If the message is delivered successfully from Outlook on the web, the original sending application or service may not be authorized by the sender domain’s SPF record. 

If the message is rejected with the same error, please ask your Microsoft 365 administrator to review the complete non-delivery report. The administrator should confirm that the sender domain has only one SPF record, that Microsoft 365 is authorized in that record, and whether the message was identified as outbound spam or routed through the High Risk Delivery Pool, as messages sent through that route may fail SPF validation. 

For more information, please refer to: Fix NDR error 5.7.23 in Exchange Online. 

Your Microsoft 365 administrator can also run a message trace in the Exchange admin center using the sender address, recipient address, and exact date and time of the failure. This can help determine how Microsoft 365 processed and routed the message. 

For instructions, please refer to: Message trace in the new EAC in Exchange Online. 

If the SPF record has already been verified and messages sent directly from Outlook on the web still receive the same error, please ask your Microsoft 365 administrator to raise a support ticket from the Microsoft 365 admin center by going to Support > Help & Support. When submitting the request, include the complete non-delivery report and the message-trace results. 

A technical support engineer can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.            

For more details, please refer to: Get support - Microsoft 365 admin   

If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin?   

Note: If you’re an end-user, please coordinate with your Office 365 Global Administrator to handle these step

 Before submitting the request, make sure Support Assistant is turned off. Some customers have reported that the Contact Support option may not appear while Support Assistant is enabled.

As shown in the screenshot, switch Support Assistant to Off, and then enter a description of the issue, scroll down and the Contact Support button should then appear, allowing you to submit the request.

Please note that I am a fellow community user and do not work for Microsoft. I do not have access to your Microsoft 365 tenant, DNS configuration, message-trace data, or Microsoft’s internal diagnostic tools. As a result, I am unable to confirm the exact cause of the SPF rejection. Any further investigation will need to be handled by Microsoft Support and, if required, the appropriate product team.