Zoho SMTP and msmtp

Zoho SMTP and msmtp

Hi there,
I was wandering how to configure msmtp. The plan is simple - use Zoho account to send mail via php mail() function.
What I have in /etc/msmtprc is:
  1. # Define here some setting that can be useful for every account
    defaults

    tls on
    tls_starttls on
    tls_trust_file /etc/ssl/certs/ca-certificates.crt

    # Settings for default account
    account default
    host smtp.zoho.com
    port 587
    auth on
    user <my@domain.com>
    password <my_pass>
    from <my@domain.com>
Every attempt to send an email gives me this:
  1.  553 Relaying disallowed as <root@localhost>

Thanks for help!