host mx.zoho.com [216.52.72.121]: 553 Relaying disallowed

host mx.zoho.com [216.52.72.121]: 553 Relaying disallowed

Hi,

I am setting up a new domain for email only hosting, the website for the domain is hosted elsewhere.

I have created the relevant accounts and mx records etc but I am cannot send emails to the account

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
 
    SMTP error from remote mail server after RCPT TO:< ******@petstails.co.uk>:
    host mx.zoho.com [216.52.72.121]: 553 Relaying disallowed

Your help would be appreciated.