554 5.2.3 MailPolicy violation Error delivering to mailboxes

554 5.2.3 MailPolicy violation Error delivering to mailboxes

I am trying to send some mail from Gmail to Zohomails, but the mail was blocked and not being delivered to zohomail accounts. 
There is a system generated that displays the following  error:

"The response from the remote server was:

554 5.2.3 MailPolicy violation Error delivering to mailboxes"

I am attaching the screenshot of the same.