cant send email relay access denied error

cant send email relay access denied error

Hi

i have created an email in zoho with my domain name and am able to recive emails
but i am not able to send  emails .when i try to send emails from zoho mail i get the below error mail

The following addresses had fatal errors -----
[Status: Error, Address: <email where i am sending>, ResponseCode 454, 4.7.1 <email where i am sending>: Relay
access denied]

can any one here let me know how to resolve this so i can send emails.
thanks

Rida