Microsoft 365 Undeliverable Email Error

Dear Make.com Community / Make.com Support,

We are trying to send an email from Exchange Online using a "Microsoft 365 (Outlook) Reply to Message“ Module. Unfortunately, we are receiving the error “550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP”. Interestingly, the message appears in the “Sent Items” folder, but shortly afterward, a bounce message is received by the sender.

As a result, we set up a new connection using an “HTTPS Make an OAuth 2.0 Request“ Module. This involves an Azure Function App with the appropriate permissions for the Graph API, connected via Application ID, Tenant ID, and Secret Key. The issue is still present.

We already tried whitelisting the sender IP addresses that triggered the bounce in the Exchange connection filter, but even the allowed IPs continue to be blocked. Microsoft EOP has not been configured.

Is there any known workaround for Microsoft 365 in this case?

Our Microsoft licensing is based on Microsoft 365 Business Standard.

Best regards,
SkyDyn Automations