email bounce

Hi,
When we want to send email to zoho accounts , we got below error in bounce:

554 5.2.3 MailPolicy violation Error delivering to mailboxes

i checked this article and, this article said:

If it is a 5.2.3, this means the message length exceeds administrative limits.

but my email dose not exceed the length and it is text is really small.

Thanks in advance

Best regard