554 5.1.8 Sender Address Blocked

554 5.1.8 Sender Address Blocked

We can not send email because "unable to send message;reason:554 5.1.8 sender addresses blocked" in this case has already been some correspondence with you.
We can send email to  addresses in zoho mail for example" info@enavak.com" but we can not send to other mail service for example ahmad_kalhor@yahoo.com
domain : farvardinkala.com
email: info@farvardinkala.com
         khalaj@farvardinkala.com
         enavak@farvardinkala.com
In previous communications we are asked to  your abuse control team would like to know the nature of business using Zoho Mail for enavak@farvardinkala.com  to proceed further. In answer to your question:our nature business is the quality control equipment and analisi calibration for metal industry and paper and cardboard industry .
we have a certificate iso/IEc/17028.
 
But no answer has been given to us
Please handle this because we use email for our business
please consider it
Regards
farvardinkala