Relaying Disallowed when sending to Zoho Mail

Relaying Disallowed when sending to Zoho Mail

Please Help.

I have a new zoho account (primobazaar.com). I have verified the domain within zoho control panel and configured the mx records on my host site to point to zoho.

When I send a mail from an external email client to test I get an error from zoho mail system reading like
SMTP -> ERROR: DATA not accepted from server: 553 Relaying disallowed





I am keen to start using my zoho mail so please advise.