SMTP -> ERROR: DATA not accepted from server: 553 Relaying disallowed

I'm facing problem of this issue "553 Relaying disallowed". I'm trying to send an email through PHP Mailer API, these are the meesage that I have gotten:

SMTP -> get_lines(): $data was ""

SMTP -> get_lines(): $str is "220 mx.zohomail.com SMTP Server ready November 3, 2016 11:46:35 PM PDT "

SMTP -> get_lines(): $data is "220 mx.zohomail.com SMTP Server ready November 3, 2016 11:46:35 PM PDT "

SMTP -> FROM SERVER:220 mx.zohomail.com SMTP Server ready November 3, 2016 11:46:35 PM PDT

SMTP -> get_lines(): $data was ""

SMTP -> get_lines(): $str is "250-mx.zohomail.com Hello hostlabs.org (md-in-56.webhostbox.net (103.21.58.201)) "

SMTP -> get_lines(): $data is "250-mx.zohomail.com Hello hostlabs.org (md-in-56.webhostbox.net (103.21.58.201)) "

SMTP -> get_lines(): $data was "250-mx.zohomail.com Hello hostlabs.org (md-in-56.webhostbox.net (103.21.58.201)) "

SMTP -> get_lines(): $str is "250-AUTH LOGIN PLAIN "

SMTP -> get_lines(): $data is "250-mx.zohomail.com Hello hostlabs.org (md-in-56.webhostbox.net (103.21.58.201)) 250-AUTH LOGIN PLAIN "

SMTP -> get_lines(): $data was "250-mx.zohomail.com Hello hostlabs.org (md-in-56.webhostbox.net (103.21.58.201)) 250-AUTH LOGIN PLAIN "

SMTP -> get_lines(): $str is "250 SIZE 53477376 "

SMTP -> get_lines(): $data is "250-mx.zohomail.com Hello hostlabs.org (md-in-56.webhostbox.net (103.21.58.201)) 250-AUTH LOGIN PLAIN 250 SIZE 53477376 "

SMTP -> FROM SERVER: 250-mx.zohomail.com Hello hostlabs.org (md-in-56.webhostbox.net (103.21.58.201)) 250-AUTH LOGIN PLAIN 250 SIZE 53477376

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 as Swati "

SMTP -> get_lines(): $data is "553 Relaying disallowed as Swati "

SMTP -> FROM SERVER:553 Relaying disallowed as Swati

SMTP -> ERROR: DATA not accepted from server: 553 Relaying disallowed as Swati

SMTP Error: Data not accepted.

What can i do?