plz i am facing this problem from last 4 days

plz i am facing this problem from last 4 days

The response was:
553 Relaying disallowed


Final-Recipient: rfc822; amir@iserver.ae
Action: failed
Status: 5.0.0
Remote-MTA: dns; mx.zoho.com. (216.52.72.121, the server for the domain iserver.ae.)
Diagnostic-Code: smtp; 553 Relaying disallowed
Last-Attempt-Date: Sat, 13 May 2017 22:07:35 -0700 (PDT)