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The default external postmaster address is set to the default accepted domain. What if you want to change the external postmaster address or check that everything is in place? In this article, you will learn how to configure the postmaster address in Exchange Server.

How to configure external postmaster address

When there’s a problem delivering a message, Exchange sends an NDR (Non-Delivery Report) to the message sender that indicates there was a problem. NDRs include a code that shows why the message wasn’t delivered and possible solutions to help get the message delivered.

There are two ways to configure the external postmaster address in Exchange Server:

  1. Exchange admin center
  2. PowerShell

Configure postmaster address in Exchange admin center

To configure the postmaster address in Exchange admin center, follow these steps:

  • Sign in to on-premises Exchange admin center
  • Click on mail flow > send connectors > … > Organization transport settings
Configure postmaster address in Exchange Server organization transport settings
  • Fill in the external postmaster address
  • Click Save
Configure postmaster address in Exchange Server external postmaster address

Keep default external postmaster address

Do you want to keep the default settings which will use the address: postmaster@default_accepted_domain?

  • Keep the external postmaster address field empty
  • Click Save
Configure postmaster address in Exchange Server external postmaster empty

Check default accepted domain

Verify the default accepted domain:

  • Click on mail flow > accepted domains
  • Verify the default domain
Configure postmaster address in Exchange Server default accepted domains

Configure postmaster address with PowerShell

To configure the postmaster address in Exchange Management Shell, follow these steps:

Run Exchange Management Shell as administrator and run the Set-TransportConfig cmdlet to set the external postmaster address.

[PS] C:\>Set-TransportConfig -ExternalPostmasterAddress postmaster1234@exoip.com

Keep default external postmaster address

Do you want to keep the default settings which will use the address: postmaster@default_accepted_domain?

Set the default external postmaster address value to $null.

[PS] C:\>Set-TransportConfig -ExternalPostmasterAddress $null

Get external postmaster address

Run the Get-TransportConfig cmdlet to verify the external postmaster address.

[PS] C:\>Get-TransportConfig | Format-List ExternalPostmasterAddress

Get default accepted domain

Run the Get-AcceptedDomain to verify the default accepted domain.

[PS] C:\>Get-AcceptedDomain | Where-Object {$_.Default -like $true} | ft -AutoSize

Name      DomainName DomainType    Default
----      ---------- ----------    -------
exoip.com exoip.com  Authoritative True

Test external postmaster address

To test that everything works as you configured, you can send a message to the Exchange organization from an external email account. Ensure that you fill in an email that is not registered. This will send an NDR report back to you.

In our example, we know that the email address 1234@exoip.com does not exist, and we will send an email to that email address.

That’s it!

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