ERROR_CODE :551

ERROR_CODE :551

Tried to send an email and got this bounce back message

  1.  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.
    ERROR_CODE :551, ERROR_CODE :This mail server requires authentication before sending mail from a locally hosted domain. Please reconfigure your mail client to authenticate before sending mail.

    Received:from mail.zoho.com by mx.zohomail.com 
       with SMTP id 1469194047971413.58044875503754; Fri, 22 Jul 2016 06:27:27 -0700 (PDT) 
    Message-ID:<15612ca10c5.1299bfbe281090.2396629066351767996@studentlife.com.cy> 
    Date:Fri, 22 Jul 2016 16:27:27 +0300 
    From: 
    User-Agent:Zoho Mail 
    To:"info" 
    Subject:Youth Pack Discount Schemes 
    Content-Type:multipart/mixed; 
       boundary="----=_Part_251132_1451642394.1469194047713"

Is this on our part or on the receivers part? if its on our part how can it be fixed asap?

Thanks