Getting error 550 5.1.0 Sender is not allowed to send from relay.zohocrm.com (R2) when set up email relay on zoho crm

Getting error 550 5.1.0 Sender is not allowed to send from relay.zohocrm.com (R2) when set up email relay on zoho crm

Hi there,

I got the problem when I wanna set up email relay on zoho crm.
here is the error message
550 5.1.0 Sender is not allowed to send from relay.zohocrm.com (R2)