Do you want to block Sender or Recipient? Your postfix config doesn’t look right. It should be
smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/sender_access
… or …
smtpd_recipient_restrictions = check_recipient_access hash:/etc/postfix/recipient_access
To block Recipient domain in PMTA, try
relay-domain bounces.yourdomain.com relay-domain otherdomain.com relay-address bounce@bounces.yourdomain.com <domain bounces.yourdomain.com> type discard </domain> <domain otherdomain.com> type discard </domain>