Custom messages in NDRs are replaced by default system messages in Office 365

Applies to: Exchange Online


You set up a transport rule in Office 365 to return a non-delivery report (NDR) that displays a custom message. However, the custom message in the NDR is overwritten by the standard NDR message. This occurs in either of the following situations:
  • The sender and recipient belong to different Office 365 organizations.
  • The sender has an Office 365 mailbox, and the recipient belongs to an external Exchange Server organization.


The DSNConversionMode parameter is not set to PreserveDSNBody.


Use the Set-TransportConfig cmdlet to set the DSNConversionMode parameter to the value of PreserveDSNBody. This transport configuration setting must be changed at the organization that receives the NDR.

To do this, follow these steps:
  1. Connect to Exchange Online by using the Remote Desktop Services module for Windows PowerShell. For more info about how to do this, see Connect to Exchange Online using remote PowerShell.
  2. Run the following command:
    Set-TransportConfig -DSNConversionMode PreserveDSNBody 


The DSNConversionMode parameter determines the format to use for delivery status notifications (DSNs). The parameter can be set to one of the following values:
  • UseExchangeDSNs
    Exchange converts the DSNs to the Exchange Server 2013 DSN format. This is the same as the Exchange Server 2010 DSN format. However, any customized text or attachments that were associated with the original DSN are overwritten if the DSN is delivered from another Office 365 organization or from an external organization.
  • PreserveDNSBody
    Exchange converts the DSNs to the Exchange Server 2013 DSN format, and the text in the body of the DSN message is retained. 
  • DoNotConvert
    Exchange does not modify the DSN message. Instead, Exchange delivers the message as a standard message.
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