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I originally had a "xxxx.onmicrosoft.com" domain and then added my own domain which was "Verified." After setting up several Emailboxes, all was well, as those emailboxes used my own domain name in their addresses. It was then reported to me that someone sent an email to a non-existent email address on my own domain and the email was returned "Undeliverable" with the original "xxxx.onmicrosoft.com" domain as the Generating Server and email@example.com as the "From:" address. I had already set my own domain as Primary in the Admin settings popup screen.
How can this be fixed so all Postmaster emails show my own domain?
Thanks for the feedback.
Thank you for your reply.
To configure the Generating Server for NDR message, please run the following cmdlet after connecting windows powershell to Exchange Online.
Set-TransportConfig -ExternalDsnReportingAuthority servername
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Do you want to change the default postmaster address from firstname.lastname@example.org to email@example.com?
If yes, you can do it referring to steps below.
1. Connect windows powershell to Exchange Online referring the steps mentioned in article below.
Use Windows PowerShell in Exchange Online
2. Run the following cmdlet to change the default postmaster address for your tenant.
Set-TransportConfig -ExternalPostmasterAddress firstname.lastname@example.org
Note: The postmaster address is a tenant/organization level setting which applies to all domains in your tenant. It's not available to set postmaster address on a domain level.
Delivery has failed to these recipients or groups:
The e-mail address you entered couldn't be found. Please check the recipient's e-mail address and try to resend the message. If the problem continues, please contact your helpdesk.
Diagnostic information for administrators:
Generating server: xxxx.onmicrosoft.com
#550 5.1.1 RESOLVER.ADR.RecipNotFound; not found ##rfc822;email@example.com
Original message headers:
Received: from mail185-tx2-R.bigfish.com (22.214.171.124) by
BY2PRD0610HT001.namprd06.prod.outlook.com (10.255.85.36) with Microsoft SMTP
The “Generating server: xxxx.onmicrosoft.com line is still incorrect and refers back to the original domain from Office365, not my own domain.
Hello Jack Sun,
The second cmdlet worked perfectly. All is well now.
Last question (I promise): Is there a way to set up a “Catch All” mailbox or account for all email sent to invalid addresses on my domain?
Thank you for your support.
No, catch-all mailboxes are not supported in Exchange Online. Generally, the catch-all mailbox is used for receiving messages sent to email addresses in a domain that do not exist. However, anti-spam filters in Exchange Online use recipient filtering to reject messages sent to mailboxes that don't exist. So, it is not necessary to create catch-all mailboxes in Office 365.
For detailed information, you can see the Exchange Online service description at following link.
Office 365 for Enterprise Service Descriptions
Thank you for your understanding.
Appreciate your response.
A catch-all mailbox IS NEEDED for any company that DOES WANT to receive ALL incoming email REGARDLESS of whether or not the email address is an existing mailbox in their domain. People (Senders) incorrectly address email messages all the time, every day. At least IF the domain portion of the address was correct, the email could flow to a catch-all mailbox for periodic review by a designated company person. THEREFORE, a catch-all mailbox SHOULD BE A CHOICE/OPTION for the Email Admin to set up IF the company desires it. An incoming email that is incorrectly addressed should NOT automatically AND always be considered spam. So, YES, IT IS NECESSARY to have the ability to create a catch-all mailbox in Office 365.
Please forward my comments to the people who made the terrible and ill-conceived decision to not allow for the creation of a catch-all mailbox.
Regards, and thanks for your understanding (nothing personal).
Thank you for your reply and the detailed feedback on the feature of Catch-All mailbox. I will forward your feedback to our product team.
Meanwhile, if you have any concern about the future, I suggest you submitting a feedback at http://g.microsoftonline.com/0BX11EN/135, your feedback will be carefully handled and appreciated. Indeed, with all the Microsoft fans’ feedback and the efforts of Microsoft related teams, many great features come out in each new product. We sincerely appreciate your enthusiasm and efforts.