Rejecting an address with our MX

[Frank Bonnet]

Hello

I wonder how to reject a particuliar address at MX machine
actually I use :
smtpd_sender_restrictions =
\check_sender_access hash:/usr/local/etc/postfix/sender_access

on the mailhub which is not "Internet visible" but I would like to 
reject with the MX machine to avoid transmission to the mailhub.

The MX does not provide local delivery, it uses transport to forward
emails to the mailhub and several other machines.

is it possible ?
if yes with which instruction ?

Thank you