only one email on domain is working - the others return does not exist host mx.zoho.com[204.141.32.121] said: 550 5.1.1

only one email on domain is working - the others return does not exist host mx.zoho.com[204.141.32.121] said: 550 5.1.1

Please help - I setup my domain
mybizz.co.za on Zoho

My main email works perfectly sales@mybizz.co.za

My other emails on same domain is rejected when sending to it from Zoho or any other email client

< grow@mybizz.co.za>: host mx.zoho.com[204.141.32.121] said: 550 5.1.1
    < grow@mybizz.co.za> User unknown (in reply to RCPT TO command)