Outlook.com custom domain error "This domain name can't be used because it contains a protected word or inappropriate language."

I am trying to add the domain sufinanciera.com.mx but get the above mentioned error.

 

I run a small financial institution of just 7 people that lends money to individuals and would like my Outlook.com e-mail to match my website address.

 

The domain will be used for communicating with clients, suppliers, and perspective clients.

 

Thanks in advance


Alejandro Glez