Learn How to Configure a Relay Connector in Exchange 2016

Anuraag Singh | Published: August 3, 2016 | Exchange Server 2016, General Info | 4 Minutes Reading

In this article I am going to discuss about how to configure a relay connector in exchange server 2016. You might know about relay connector in earlier versions of Exchange server. Therefore you may find little change in SMTP relay configuration. Lets proceed for the discussion. Configure a Relay Connector

Exchange Server 2016 offers various services for users that are required to perform various functions such as supports office 365 hybrid, Outlook availability on web, etc. Out of which one such feature is to configure a relay connector in Exchange 2016 to provide mapping between different ISPs for sending and receiving of email messages. Nowadays, in almost every organizations various applications or devices are used, which requires SMTP services to perform the functions. In the following discussion we, will discuss the way to configure a connector in Exchange 2016.

Technique to Perform Configuration of Relay Connector

There are mainly two types of SMTP relay scenarios in Exchange Server 2016 as mentioned to configure relay connectors.

Internal SMTP Relay

It includes the applications or devices, which require sending of only email messages to internal recipients in the Exchange organization. When Exchange Server 2016 is installed, the setup routine generates the receive connectors automatically. It is pre-configured that is used in receiving emails from senders to internal recipients. It permits inbound internet email to be received from server that is suitable for internal relay. It can be tested by making SMTP connection by using Telnet and allotting SMTP commands. There is no precise configuration required on server in this case, though it is recommended to use DNS alias in place of real server name. As it permits to configure all applications or devices with DNS alias and further it allows moving that DNS alias to point at different Exchange server at the migration time.

External SMTP Relay

It includes the devices or applications, which requires sending of email messages to external recipients. It can be tested by using Telnet to send email message from internal address to external recipient. While testing user receives an error code:
Due to which, the receive connector will not permit anonymous and unauthenticated sender to relay to external domain names. It avoids the server from being misused as open relay. To resolve this, there are two techniques mentioned, which permits the applications or devices to send external recipients.

  • Using Authentication
    Exchange Server 2016 has a receive connector, which is used by clients who needs to send mails via SMTP. It requires minimal configuration for its proper working. It will be clear with an example, suppose the user has already configured an SSL certificate and added DNS alias for SMTP applications and devices for utilization. Users can also set TlsCertificateName for receiving connector. They can use Get-ExchangeCertificate for identifying the thumbprint of SSL certificate.
    For testing the client frontend connector for sending emails, PowerShell’s Send-MailMessage cmdlet can be used in place of Telnet. Firstly, capture valid credentials to utilize for authentication. Then, use the Send-MailMessage cmdlet with parameters for identifying the server, to and from address, port number, and subject line. If the email is received successfully via external recipient then, it means that any application or devices on network can use authenticated SMTP. It can be set up to utilize that connector on port 587 on Exchange Server 2016.
  • Using Anonymous Connection
    When authenticated SMTP is not an option, then user creates a new receive connector on server, which allows anonymous SMTP relay from the defined list of IP addresses or ranges. In Exchange Admin center navigate to flow of mails, receive connectors later, and follow the discussed steps.

    1. Choose the server, to build the new receive connector on >> click on ‘+’ button for starting the wizard.
    2. Give a name to the new connector. Set Role to ‘Frontend Transport’, and type to ‘Custom’.
    3. Network Adapter Bindings represents IP and port that server for connections will listing on. The multiple received connectors that are on the frontend transport services are on the same port of TCP 25.
    4. Now, from remote network settings remove the default IP range and add the specific IP address or range, which is required for anonymous SMTP relay.
    5. Click on the option Finish to complete the wizard.

Now the user can test connectors by using Telnet from IP address, which was added to remote network settings of the received connector.


As you have read the discussion about “how to configure a relay connector in exchange server 2016”. On the basis of discussion I can say that you would have learnt the described topic.

It is to be noted that users can configure a relay connector in Exchange 2016 for sending and receiving mails. We believe, that with the help of the above discussion, you will be able to configure a relay connector in server successfully.