Exchange Receive connector to relay emails from 3rd party internet services

Muhammad Hussain 201 Reputation points

How we can create an Exchange Receive connector to relay emails from 3rd party internet services or do we need to do any other changes on Exchange? I just want to send an email from i.e. AWS application using on Prem exchange and email addresses. How it is possible. what configurations are required on the exchange server? Environment: 2 DC's2 Exchange servers 2013 CAS+Mailbox both are internet-facing servers.1 Edge server. I Created a relay on the mailbox server with authentication and without authentication but it is saying unable to relay. 

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. Aaron Xue-MSFT 2,586 Reputation points Microsoft Vendor

    Hi @Muhammad Hussain ,

    You could create an Open Relay to allow 3rd party send emails from your exchange server.

    And make sure that allow anonymous relay only by the specified network hosts as identified by their IP addresses.


    You could get more details from this link.

    Please Note: Since the web sites are not hosted by Microsoft, the links may change without notice. Microsoft does not guarantee the accuracy of this information.

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  1. Andy David - MVP 142.8K Reputation points MVP

    If you want to relay then follow:

    The key is knowing what external IP address AWS is using to scope the custom receive connector to, otherwise you would allow anything on the internet and that would be really bad of course!

    Do not do this unless you trust that external IP.

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  2. Muhammad Hussain 201 Reputation points

    In the above link it seems they are creating rely on to use internally but in my case, I want to send email from the internet using my exchange hostname. I want to create rely on incoming internet users.

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  3. Muhammad Hussain 201 Reputation points

    getting below error.

    550 5.7.1 Unable to relay

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  4. Andy David - MVP 142.8K Reputation points MVP

    You would still need to use that link - but only if you trust that sending IP. If not, then you DO NOT create a relay for the external IP.
    Why the need to relay internet mail like this?
    If this is some alert email, then create an account and have the system authenticate on port 587 like a user

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