553 Relaying disallowed SMTP Error: data not accepted

553 Relaying disallowed SMTP Error: data not accepted

I am configuring my website to use my zoho mail for my contact form.

I am using phpmailer but this exits with the following error:

  1. SMTP ERROR: DATA END command failed: 553 Relaying disallowed SMTP Error: data not accepted. Mailer Error: SMTP Error: data not accepted.
Why its saying Relaying disallowed? And how i can fix this, or maybe you people can.