Microsoft 365 Trial Tenant – 550 5.7.708 “Access denied, traffic not accepted from this IP”

Hi @Hamza,

Based on my research, the 550 5.7.708 "Access denied, traffic not accepted from this IP" error means Exchange Online is rejecting outbound mail because the sending IP currently has a low reputation. Per Microsoft's documentation, this is more likely to affect new customers, including Microsoft 365 trial tenants, and the IP does not have to appear as a public address in the NDR for the error to apply.

Below are my responses to your questions. I hope you'll have a chance to review them at your convenience:

1/ Can the restriction be removed on a trial tenant?

Potentially, but Microsoft Support intervention is required. Microsoft’s guidance states that administrators who receive a 5.7.708 error during a trial subscription should contact Microsoft Support to request an IP address exception until Exchange Online licenses are assigned.

It is also worth confirming that the affected user has an Exchange Online license assigned and that the mailbox has completed provisioning. If the license is already assigned, include that information in the support request.

2/Is there anything I can check or reset myself in Exchange Online / Defender?

There is no documented tenant-side setting in Exchange Online or Microsoft Defender that can reset a genuine 5.7.708 IP-reputation block. Microsoft’s guidance for this error on a trial tenant is to contact Microsoft Support and request an IP address exception.

3/If support intervention is required, how can I raise a support request while still on a trial subscription?

A Microsoft 365 administrator can also open a support request directly from the Microsoft 365 admin center by selecting Help & support in the lower right corner of the page.

Tips: You can switch off the Support Assistant as shown in the screenshot, then type a few short characters into the search box and select Get Help. After that, wait for the Contact Support button to appear and click it. At the final step, be sure to clearly describe your request in the description fields so the support engineers can quickly understand your issue and assist you more effectively.  

I hope the information above helps clarify a few points. If you need any further assistance, please feel free to get back to me and I'll be happy to help within my scope.

Thank you for taking the time.

If the answer is helpful, please kindly click "Yes" button below. If you have extra questions about this answer, please click "Comment".    

Note: Please follow the steps in the forum documentation to enable e-mail notifications if you want to receive the related email notification for this thread.