Invalid Address, ERROR_CODE :550, ERROR_CODE :Requested action not taken: mailbox unavailable or not local

Invalid Address, ERROR_CODE :550, ERROR_CODE :Requested action not taken: mailbox unavailable or not local

Hello,
I recently started my domain' email account with zoho mail services, but when I am trying to send emails, an email is send back to me saying this : 


This message was created automatically by mail delivery software. 
A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. 

legal@archangel.gr  Invalid Address, ERROR_CODE :550, ERROR_CODE :Requested action not taken: mailbox unavailable or not local 


Received:from mail.zoho.com by mx.zohomail.com 
    with SMTP id 1414997605299910.2526441982504; Sun, 2 Nov 2014 22:53:25 -0800 (PST) 
Message-ID:<149746dfb81.ceed 50a6190237.6249109786912721016@woolbear.com > 
Date:Sun, 02 Nov 2014 22:53:25 -0800 
From:Wool Bear < info@woolbear.com > 
User-Agent:Zoho Mail 
To:< legal@archangel.gr > 
Subject:Demo Submission 
Content-Type:multipart/alternative; 
    boundary="----=_Part_245988_1100800597.1414997605248"