As Exchange Administrators work to understand all the nuances of Exchange Online, either the older Office 365 (2010) or the newer Office 365 (2013), they have probably asked “What about my Postmaster account, where is it, how do I configure or manage it? There is no Postmaster account that I can find, so how does this work?”.
In reading through the following, written in 2012, that EXO Admin’s get a default Postmaster account/setting used for your Exchange Online Tenant: http://www.msdigest.net/2012/03/how-to-set-the-postmaster-address-in-office-365/:
When viewing Exchange Online TransportConfig, you will find no entries for the Postmaster account. However if you send a “bad” mail into your Exchange Online tenant, such as firstname.lastname@example.org, you will receive an NDR from email@example.com, showing that Exchange Online has the Postmaster setting covered.
- Connect to Exchange Online via Remote PowerShell
- Run the following command, which will set your Exchange Online Postmaster setting for your tenant:
Set-TransportConfig -ExternalPostmasterAddress firstname.lastname@example.org