Can't Receive Emails in Zoho

Can't Receive Emails in Zoho

I have added the MX settings and set up the SMTP for jacobs@essentialvendingtx.com, but I cannot receive messages at that address. Emails that attempt to send are met with errors similar to this one:

  jacobs@essentialvendingtx.com
    host  sebackend1.registrar-servers.com  [38.101.213.199]
    SMTP error from remote mail server after RCPT TO:< jacobs@essentialvendingtx.com >:
    554 5.7.1 < jacobs@essentialvendingtx.com >: Relay access denied

Action: failed
Final-Recipient:  rfc822;jacobs@essentialvendingtx.com
Status: 5.0.0
Remote-MTA: dns;  sebackend1.registrar-servers.com
Diagnostic-Code: smtp; 554 5.7.1 < jacobs@essentialvendingtx.com >: Relay access denied

Please help me fix this?