How to set smtp relay from one exchange organization to another organization and Prerequisites to check ####################################### Exch2019- Copy.pdf Hello guys, i have a scenario for exchange server , attached the visio for better understanding Two environments, IT and OT IT Domain (abc.com) Exchange server 2019 Hybrid setup with M365 hosting user mailboxes and mail flow via M365 OT Domain (xyz.com) Exchange server 2019, used for the purpose of SMTP relay for applications I want to configure OT domain exchange server to send email to the receipients in IT domain please let me know if any other steps are required apart from the below mentioned => accepted domain of abc.com => partner send connector and connect IT domain exchange server for sending the emails to the receipients => receive connector setting is default with anonymous senders

Hi @mohammed arifuddin, Since in IT Domain the mail flow is routed via Exchange Online, you can create a custom receive connector in Exchange Online for SMTP relay from OT domain. Please follow these steps: Option 3: Configure a connector to send mail using Microsoft 365 or Office 365 SMTP relay If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

How to set smtp relay from one exchange organization to another organization and Prerequisites to check

Accepted answer

Kael Yao-MSFT 37,651 Reputation points Microsoft Vendor

2023-06-26T07:06:07.7866667+00:00

Hi @mohammed arifuddin,

Since in IT Domain the mail flow is routed via Exchange Online, you can create a custom receive connector in Exchange Online for SMTP relay from OT domain.

Please follow these steps: Option 3: Configure a connector to send mail using Microsoft 365 or Office 365 SMTP relay

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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mohammed arifuddin 25 Reputation points

2023-06-26T11:03:51.52+00:00

Hello ,

Thanks for your response, i cannot use the option suggested by you as i dont have internet in OT domain.

So my option would be to relay on IT domain exchange server on port 25.

please let me know if any other steps are required apart from the below mentioned

=> accepted domain of abc.com in OT domain exchange server

=> send connector and connect to IT domain exchange server for sending the emails to the receipients

=> receive connector setting is default with anonymous senders

Regards,

Arif

Kael Yao-MSFT 37,651 Reputation points Microsoft Vendor

2023-06-27T07:59:34.4066667+00:00

Thanks for the clarification.

Sorry I missed the network topology.

If the goal is to relay emails from OT domain to IT domain, to me you may only need to:

1.create a receive connector in OT domain to allow applications to relay emails

Follow this link: Allow anonymous relay on Exchange servers

2.create a send connector in OT domain and set IT domain as smart host (send connector and connect to IT domain exchange server for sending the emails to the receipients)

Kael Yao-MSFT 37,651 Reputation points Microsoft Vendor

2023-06-30T05:44:15.2133333+00:00

Hi @mohammed arifuddin

I am writing here to confirm with you how thing going now?

Please let us know if you would like further assistance.

mohammed arifuddin 25 Reputation points

2023-07-02T05:19:41.9133333+00:00

Hello , @Kael Yao-MSFT

Thank you for the response so we need to perform the below steps.

1.create a receive connector in OT domain to allow applications to relay emails

Follow this link: Allow anonymous relay on Exchange servers

2.create a send connector in OT domain and set IT domain (mail.abc.com or ip) as smart host (send connector and connect to IT domain exchange server for sending the emails to the receipients)

So accepted domain of abc.com in OT domain exchange server is not required?

Regards,

Arif

Kael Yao-MSFT 37,651 Reputation points Microsoft Vendor

2023-07-03T05:37:18.4533333+00:00

So accepted domain of abc.com in OT domain exchange server is not required?

If OT domain Exchange server doesn't host IT domain recipients, to me there is no need to create accepted domain (abc.com) in OT domain as emails would be relayed to IT domain Exchange server through the send connector.

mohammed arifuddin 25 Reputation points

2023-07-03T05:46:30.68+00:00

Hello @Kael Yao-MSFT

Thank you for the reply, yes understood.

The scenario is OT domain exchange servers will do the smtp relay for the applications in OT domain and the recipients of the relay are in IT domain exchange server.

Kael Yao-MSFT 37,651 Reputation points Microsoft Vendor

2023-07-03T06:00:05.0266667+00:00

Glad to help.

Do you have other questions on this topic which I can help you with?

If this question has been answered, please accept the helpful replies as answers.

This will make answer searching in the forum easier and be beneficial to other community members as well.

mohammed arifuddin 25 Reputation points

2023-07-03T06:08:56.18+00:00

Yes sure, thank you !!

mohammed arifuddin 25 Reputation points

2023-07-17T10:23:32.0133333+00:00

@Kael Yao-MSFT Hello again,

Can you kindly provide the detailed steps in creating send connector?

We have created send connector with custom option and provided the details to connect but its not working

We have to follow this link? https://learn.microsoft.com/en-us/exchange/configure-a-cross-forest-send-connector-exchange-2013-help

Regards,

Arif
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