Exchange - Undeliverable Emails

Copper Contributor

I have a single Microsoft Exchange account (to allow me to sync addresses, calendars, notes etc across a range of windows and android devices).

 

The email for this account is xx@domainname.onmicrosoft.com.

 

I also have a number of email adressess at my company domain  : xx@domain.com

 

If I try to send emails from xx@domainname.onmicrosoft.com to any email address at xx@domain.com I get an "undeliverable" message stating :

 

"Your message to xx@domainname.com couldn't be delivered.   xx wasn't found at domainname.com."

 

Any suggestions as to why this is happening would be most welcome.

 

Thanks

SB

 

5 Replies

@sjb66 

 

Hi, is the xx@domain.com added to your Office 365 tenant as an accepted domain please, or is it residing elsewhere, such as an on-premises Exchange Server?

@PeterRising  There is no connection between them at all apart from the fact I access both of them via Outlook on Microsoft 365.  

 

  xx@domian.com is on a 3rd party supplier, web host server, and is not an "exchange" server.

 

 

 

 

 

 

Which server is generating the NDR? It might be a simple case of you having a matching contact within your directory, causing the message to be routed incorrectly. Also, run a message trace: https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/message-trace-scc?view=o...

Hello @sjb66 

Could you please check the email delivery using the online Microsoft tool : testconnectivity.microsoft.com and see the exact issue you face

 

Thanks,

Manu

@Vasil Michev @manuphilip 

 

Thanks for the suggestions. I had a look at the Office 365 Security & Compliance message trace utility and I wasn't able to run it but I think it shows where the problem is.

 

I'm logged in as xx@domainname.onmicrosoft.com but the default queries in the message trace section all refer to xx@domainname.com clearly the system is somehow confusing the two accounts.

 

My primary Microsoft account (for Microsoft 365, Onedrive etc) is under xx@domainname.com . the Exchange account is (because it has to be) under xx@domainname.onmicrosoft.com .