Exchange 2019 / Edge server with working EdgeSynchronization - Relay problem

Johnny Broe 436 Reputation points
2021-03-24T12:47:38.387+00:00

We have an on-premises Exchange 2019 server with a subscribed Edge Transport server.

This is working fine.

I now need to allow an external Exchange server to use us as a relay to send external mails. This server is not part of our Exchange organization or AD domain, but we trust it sufficiently to implement this requirement.

I have added a new FrontEndTransport Receive Connector on our Exchange server, configured it for Anonymous access and set the Scoping to only accept email from the IP address of the remote Exchange server. I have also deselected all authentication mechanisms for the connector - i'm not sure if that's correct.

Unfortunately when I send mails from the external server I keep getting NDRs along the lines of: [FQDN on Edge server] #550 5.7.54 SMTP; Unable to relay recipient in non-accepted domain ##

I have made sure that the Edge Subscription is synchronized but the problem persists.

Some picture of my configuration: ![81195-image.png][1] ![81138-image.png][2] ![81187-image.png][3]

Any hints would be nice?

Best Regards John B

[1]: /api/attachments/81195-image.png?platform=QnA [2]: /api/attachments/81138-image.png?platform=QnA [3]: /api/attachments/81187-image.png?platform=QnA

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Eric Yin-MSFT 4,386 Reputation points
    2021-03-26T09:31:57.897+00:00

    Hi,
    Seems I forgot the edge server.
    Is your A record pointing to your edge server? And you created the receive connector on mailbox server?
    For Inbound mail flow with Edge Transport servers, it's received by edge server first, than delivered by default Send connector named "EdgeSync - Inbound to <Active Directory site name>" sends the message to a Mailbox server.
    So I suppose you should create a customize connector on Edge server with remote IP added to "Remote network settings" .


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  1. Eric Yin-MSFT 4,386 Reputation points
    2021-03-25T07:29:46.46+00:00

    Hi,
    Enable protocol logging for the customized receive connector and check the log, make sure you are accessing your Exchange server via correct connector:
    81415-3.png


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  2. Johnny Broe 436 Reputation points
    2021-03-25T14:44:51.833+00:00

    Hi Eric
    thanks for your response.
    I have enabled protocol logging on receive connector "Default Frontend Transport" and on "Mail Relay".
    In the log I can see it is only receive connector "Default Frontend Transport" there are used.
    My receive connector "Mail Relay" is not used.
    I have tried to disable "Default Frontend Transport" but then I am unable to receive mail.
    I have tried to change the "Default Frontend Transport" so the wan Ip address there are on the "Mail Relay" not are included, but I still receive mail via "Default Frontend Transport".
    A hint would be nice
    Best Regards
    John B


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