I got this following error when my whm root@xxx.com send an notification to my zoho email.

here is the detail log:

AES128-SHA:128 CV=yes: SMTP error from remote mail server after RCPT TO:<admin@host.natanetwork.com>: 552 5.1.1 <admin@host.natanetwork.com> Mailbox delivery failure policy error

I dont know what is 552.5.1.1 ?? so i guess there is something wrong with zoho email.

because when I change the email to gmail for instance, it works perfectly.

but when I set email notification send to zoho email account, the error shows like that.

help me..

thanks