email going out but not hitting in box MP C6004

[slimslob]

i send it to many different domains same result

What if you send to the same domain as the authentication email address. If it goes through then it would appear that your customer is setup to use Option 2 of the following link. If the C6004 is not properly supporting TLS/StartTLS then they may have to use Microsoft's relay server, Option 3 of the following link.

Warning: Much of what is discussed in the following link, especially Option 2 and Option 3 should be done by the customer's IT. If you are not the customers IT, getting it working is not your responsibility. Provide the link to the customer or their IT and let them handle the setup.

How to set up a multifunction device or application to send email using Microsoft 365 or Office 365 | Microsoft Docs