I am trying to send mail through my Drupal system. The details used are as follows:

SMTP Server: smtp.zoho.com

Port:465

Use SSL - Enabled

SMTP Authentication: Enabled.

From email address:  contact@taxsubmit.in

The error is 553: relaying disallowed (details given below). Please help.

SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "220 mx.zohomail.com SMTP Server ready July 21, 2014 11:13:52 AM PDT " 
SMTP -> get_lines(): $data is "220 mx.zohomail.com SMTP Server ready July 21, 2014 11:13:52 AM PDT " 
SMTP -> FROM SERVER:220 mx.zohomail.com SMTP Server ready July 21, 2014 11:13:52 AM PDT 
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "250-mx.zohomail.com Hello taxsubmit.in (198.199.104.79 (198.199.104.79)) " 
SMTP -> get_lines(): $data is "250-mx.zohomail.com Hello taxsubmit.in (198.199.104.79 (198.199.104.79)) " 
SMTP -> get_lines(): $data was "250-mx.zohomail.com Hello taxsubmit.in (198.199.104.79 (198.199.104.79)) " 
SMTP -> get_lines(): $str is "250-AUTH LOGIN PLAIN " 
SMTP -> get_lines(): $data is "250-mx.zohomail.com Hello taxsubmit.in (198.199.104.79 (198.199.104.79)) 250-AUTH LOGIN PLAIN " 
SMTP -> get_lines(): $data was "250-mx.zohomail.com Hello taxsubmit.in (198.199.104.79 (198.199.104.79)) 250-AUTH LOGIN PLAIN " 
SMTP -> get_lines(): $str is "250 SIZE 25000000 " 
SMTP -> get_lines(): $data is "250-mx.zohomail.com Hello taxsubmit.in (198.199.104.79 (198.199.104.79)) 250-AUTH LOGIN PLAIN 250 SIZE 25000000 " 
SMTP -> FROM SERVER: 250-mx.zohomail.com Hello taxsubmit.in (198.199.104.79 (198.199.104.79)) 250-AUTH LOGIN PLAIN 250 SIZE 25000000 
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "334 VXNlcm5hbWU6 " 
SMTP -> get_lines(): $data is "334 VXNlcm5hbWU6 " 
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "334 UGFzc3dvcmQ6 " 
SMTP -> get_lines(): $data is "334 UGFzc3dvcmQ6 " 
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "235 Authentication Successful " 
SMTP -> get_lines(): $data is "235 Authentication Successful " 
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "250 Sender OK " 
SMTP -> get_lines(): $data is "250 Sender OK " 
SMTP -> FROM SERVER:250 Sender OK 
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "250 Recipient OK " 
SMTP -> get_lines(): $data is "250 Recipient OK " 
SMTP -> FROM SERVER:250 Recipient OK 
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "354 Ok Send data ending with . " 
SMTP -> get_lines(): $data is "354 Ok Send data ending with . " 
SMTP -> FROM SERVER:354 Ok Send data ending with .  
SMTP -> get_lines(): $data was "" 
SMTP -> get_lines(): $str is "553 Relaying disallowed " 
SMTP -> get_lines(): $data is "553 Relaying disallowed " 
SMTP -> FROM SERVER:553 Relaying disallowed 
SMTP -> ERROR: DATA not accepted from server: 553 Relaying disallowed 
SMTP Error: Data not accepted.