553 Relaying disallowed

553 Relaying disallowed

I got an error like this while sending mail..
 
and my log report is below

Jul  6 11:20:17 administrator-Inspiron-3542 postfix/master[6742]: terminating on signal 15
Jul  6 11:20:18 administrator-Inspiron-3542 postfix/master[6942]: daemon started -- version 2.11.0, configuration /etc/postfix
Jul  6 11:20:22 administrator-Inspiron-3542 postfix/pickup[6945]: 16EB044009C: uid=1000 from=<administrator@administrator-Inspiron-3542>
Jul  6 11:20:22 administrator-Inspiron-3542 postfix/cleanup[6952]: 16EB044009C: message-id=< 20160706055022.16EB044009C@administrator-Inspiron-3542.fantain.com>
Jul  6 11:20:22 administrator-Inspiron-3542 postfix/qmgr[6946]: 16EB044009C: from=<administrator@administrator-Inspiron-3542>, size=451, nrcpt=1 (queue active)
Jul  6 11:20:27 administrator-Inspiron-3542 postfix/smtp[6954]: 16EB044009C: to=< user@gmail.com>, relay=smtp.zoho.com[165.254.168.48]:587, delay=5, delays=0.11/0.1/3.8/0.96, dsn=5.0.0, status=bounced (host smtp.zoho.com[165.254.168.48] said: 553 Relaying disallowed as user@domain.com (Administrator) (in reply to end of DATA command))

Thanks in Advance