Wrong Recipient Internal Domain (mydomain).mail.onmicrosoft.com

Question

I have users with Rejected emails from a Microsoft 365 dynamic group because the recipient domain automatically change to another domain that is not configured.

Example:

P2 sender: User1@company.domain.com

Return-path: User1@company.domain.com

Recipient domain: mymailcompanydomain.mail.onmicrosoft.com
To: User 2 user2@company.domain.com

Delivery action: Blocked

Status

Office 365 received the message that you specified, but couldn't deliver it to the recipient (‎User2@mymailcompanydomain.mail.onmicrosoft.com) due to the following error:

Error: ‎550 5.4.1 Recipient address rejected: Access denied. [CY4PEPF0000EE36.namprd05.prod.outlook.com 2023-10-25T14:34:47.437Z 08DBD3116150CF38]‎

A non-delivery report (NDR) message was sent to ‎User1@company.domain.com. The NDR might provide more details about why the email message wasn't delivered and how to fix the issue.

In this case after a deep search in my configuration the recipient email is been blocked due to an incorrect domain. I have checked in the Admin/Domain

Answer 1

Hi @Anielka Oliveros

Is this dynamic group a dynamic Microsoft 365 group or a dynamic distribution list?

How to distinguish in Exchange Admin Center:

From your post the sender is an internal sender inside your organization.

Please post the following settings of this group:

(Don't forget to hide your personal information for security)

1.Settings>Delivery management:

2.General>Email Addresses

Thanks in advance for the information.

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