Office 365 NDR Messages using Null address

Occasional Contributor

Hi all,


I was wondering if you could help me below Scenario.


External user sends email to 0365 user, that mailboxes doesn’t exist anymore. NDR will be sent to the external sender.

So that NDR will have the from address in the header as null address <>.


I want to set up a transport rule which would be like follows;


If the sender from address is <> and inside  organisation and message is addressed to outside organisation change the from address to or or any given address.


My aim is to stop NDR using null address.




4 Replies

It will not be null, it will be the default value You can change it by modifying the value specified under ExternalPostmasterAddress:


Set-TransportConfig -ExternalPostmasterAddress


Keep in mind that the format used in the NDR message will also depend on the sender's email system and in some cases the address might be replaced.


Thanks Vasil.


Does this apply to OOO messages as well?





Not sure what you mean by that. OOO messages are generated with the address of the user?

Within the header, the envelope address is a null address at times