question

amillsuk-1089 avatar image
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amillsuk-1089 asked KyleXu-MSFT commented

Trying to route mail to custom domain that sits ON PREM

Hi,

Briefly.

We have a server sat within our organisation (virtual server - 10.10.10.111) that needs to accept emails that in turn are processed into invoices on a financial system.

We have mailboxes that sit on our on premise hybrid server that receive invoices from external senders that then forwards them to a custom domain/email address (test@invoice-test-contoso.co.uk)

We have a contact setup on premise with that email so it can be forwarded in that way (test@invoice-test-contoso.co.uk).

We then have a custom send connector setup that looks for any mail sent to the domain invoice-test-contoso.co.uk and forwards it to a smart host (10.10.10.111) which is the above mentioned virtual server.

The above process works perfectly fine. However;

When I move the mailbox to O365 and try to do the same thing, I get the error: Status code: 550 5.7.1

On O365 I have a remote domain setup that accepts forwarding as well as have forwarding turned on for the original domain of the external facing mailbox.

I have a connector setup to route mail to the on premise server name. (TLS with any digital cert)

I have a transport rule that says any mail that is sent to the domain of invoice-test-contoso.co.uk use the above connector - this should in theory mean that when the external facing mailbox (sitting in our O365 organization) forwards to test@invoice-test-contoso.co.uk - it should route the mail to the above connector which should then route the mail to our on premise hybrid server which should then deal with the mail accordingly, but it clearly doesn't.

I'm at a bit of a loss and need some advice. Mail flow theory;

Mail comes into external facing mailbox (o365) > forwards to test@invoice-test-contoso.co.uk > uses connector to route to smart host of on premise hybrid > should use send connector on premise to forward to virtual server

The custom domain invoice-test-contoso.co.uk doesn't exist anywhere. It is simply setup as a receive address on the virtual server. It isn't an owned domain and has never needed to be.

Cheers

office-exchange-server-mailflow
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What is the full NDR?
Status code: 550 5.7.1

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@amillsuk-1089

Any update about this thread now?

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1 Answer

KyleXu-MSFT avatar image
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KyleXu-MSFT answered

@amillsuk-1089

I want to confirm with you that whether those information below are correctly:
1. The "test@invoice-test-contoso.co.uk" is an virtual domain for your Exchange on-premise, the mailbox is hosted on your Exchange on-premises.
2. You have enabled "Enable forwarding" for one Exchange online mailbox, all emails that sent to this Exchange mailbox will be forward to the Exchange on-premise mailbox.

If so, I would suggest you try to send email from your Exchange online mailbox to the “test@invoice-test-contoso.co.uk” directly. Check whether could send email to the virtual domain. If you cannot send email successfully, I think you may need to change it to an owned domain and verify on your Exchange online.

I also suggest you try to set another external domain as "forward email address" for this Exchange online mailbox, if email cannot forward successfully, please provide the detailed NDR information to us.


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