Need Assistance with Universal MX Server for Email Filtering Proxy in Cross-Region Exchange Online Configuration

Lior Tomer 60 Reputation points

We have a cloud service (PaaS), which filters customer's emails sent to Exchange Online. Customers create an outbound SMTP connector and a rule to redirect their messages to us. We filter them and return by a "direct send". And here is the problem - our solution is not a relay but a proxy. It can connect only to a single smart host for all customers, so we use our company's MX record to return emails to all customers. When a customer is outside our organization's region (West Europe), we cannot return the message - we get ATTR35 (wrong region). We tried to create an O365 "relay" - an inbound connector from "partner" organization (our fixed IP) to O365. Does not help.

Do you have a universal MX server, which can accept message to any address. If not, which options do we have?

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  1. Shaofan Lv-MSFT 6,915 Reputation points Microsoft Vendor

    Hello Lior

    There seems to be no such universal MX server. This seems like a complex scenario. If possible, would you consider opening a ticket with MS support?



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