Since we used 8.0.0 we didn't had any problems for adding "check_recipient_access hash:/opt/zimbra/postfix/conf/protected_recipients" (into smtpd_recipient_restrictions options) in the postfix's main.cf and it worked just fine.

Now, we've upgraded to 8.0.3 and adding this line to postfix, and reloading the postfix system, the line is automatically removed.
Any ideas how to add this check for some groups that we need to be closed for the outer world?