I am using outlook.com with the domain ending onecreation.sg and are able to receive all mails on both webbased outlook.com and outlook 2010 client. 

However, there is only one domain name we are not able to receive. This domain is not in the blocked sender list, and in fact have already added it to safe sender list like this: @itoki.com.sg. 

I did not attempt any forwarding setting also.

There is not any error message from both sides, which is from itoki.com.sg and onecreation.sg. 

In fact, from itoki.com.sg, the message is classified as SENT.

This issue only occurs when we migrate our email to outlook.com.

Please help, we are getting alot of ridicules from our customer, itoki.com.sg. 

Thank you