Configure the external postmaster address in Exchange Online

Exchange Online

Applies to: Exchange Online

Topic Last Modified: 2016-04-29

Use the procedure here to change your organization’s external postmaster address. The external postmaster address is used as the sender for system-generated messages and notifications sent to message senders that exist outside your Microsoft Exchange Online organization. An external sender is any sender that has an email address in a domain that isn't configured as an accepted domain in your organization.

By default, the value of the external postmaster address setting is blank. This default value sets the external postmaster address to the value postmaster@<Default accepted domain> for your organization.

  • Estimated time to complete: 15 minutes

  • You need to be assigned permissions before you can perform this procedure or procedures. To see what permissions you need, see the "Transport configuration" entry in the Mail flow permissions topic.

  • You can only use the Shell to perform this procedure. To learn how to use Windows PowerShell to connect to Exchange Online, see Connect to Exchange Online PowerShell.

  • For information about keyboard shortcuts that may apply to the procedures in this topic, see Keyboard shortcuts in the Exchange admin center.

To configure the external postmaster address, use the following syntax.

Set-TransportConfig -ExternalPostmasterAddress <postmaster address>

For example, to set the external postmaster address to the value, run the following command

Set-TransportConfig -ExternalPostmasterAddress

To return the external postmaster address to the default value, run the following command:

Set-TransportConfig -ExternalPostmasterAddress $null

To verify that you have successfully configured the external postmaster address, do the following:

  1. Run the following command to verify the external postmaster address value:

    Get-TransportConfig | Format-List ExternalPostmasterAddress
  2. From an external email account, send a message to your Exchange organization that will generate a delivery status notification (DSN). To ensure a DSN will be sent from your external postmaster address, you can configure a transport rule to send a non-delivery report (NDR), which is a type of DSN, for a message from that sender that contains specific keywords. Verify that the sender's email address in the DSN matches the external postmaster address you specified.

Having problems? Ask for help in the Exchange forums. Visit the forums at Exchange Server, Exchange Online, or Exchange Online Protection.