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JohnnyBroe-3637 asked EricYin-MSFT commented

Exchange 2019 / Edge server with working EdgeSynchronization - Relay problem

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 ![81138-image.png][2] ![81187-image.png][3]

Any hints would be nice?

Best Regards John B

office-exchange-server-mailflow
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EricYin-MSFT avatar image
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EricYin-MSFT answered EricYin-MSFT commented

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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Hi Eric
thanks for all your help :-)

Case solved by making a new receive connector on Edge server and let this new connector forwarding mail for one WAN IP address!!

Have a nice day

Best Regards

John B

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Hi,
Would you accept it as answer to close it up? Thanks in advance.

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EricYin-MSFT avatar image
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EricYin-MSFT answered

Hi,
Enable protocol logging for the customized receive connector and check the log, make sure you are accessing your Exchange server via correct connector:
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JohnnyBroe-3637 avatar image
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JohnnyBroe-3637 answered EricYin-MSFT converted comment to answer

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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Hi,
Here is what I've tested:
Add the Ip address ("remote-endpoint" in Protocol log) to "Remote network settings" of your connector "Mail Relay", then disable "Default Frontend Transport" and try telnet commands on your remote Exchange server.

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Hi Eric
When I added the remote endpoint IP address to the "Mail Relay" connector, it initially happened that mail jumped up the Edge server and did not get through to the mailbox. And in the log file, the receiving connector switched to "Mail Relay" and it looked like this:
protocollog1.png

I could configure the "Mail Relay" connector so that it was able to receive mails instead of the "Default Frontend" connector but I was still not able to relay. It looked like this:
protocollog2.png

Between Edge server and Mailbox is the communication between Edge server local ip and Mailbox local IP, so how will it be possible for the "mail relay" connector to recognize a WAN IP address and allow Relaying?

I have tried to enable log on the Edge server and here I can see the WAN addresses :-)

81804-protocollog1.png81842-protocollog2.png


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