This error typically occurs with newly created Microsoft accounts, where Microsoft has restrictions on sending emails via third-party services. The error message "5.7.708 Service unavailable. Access denied, traffic not accepted from this IP" indicates that your account's ability to send emails through third-party services has been temporarily blocked by Microsoft.
What To Do:
You need to manually contact Microsoft support through the Microsoft 365 admin center.
Request them to unblock your account for sending emails via third-party services.
Once Microsoft has processed your request, you should be able to send emails without encountering this error.
