not working smtpd_recipient_restrictions implementation

[Eric Smith]

Dear fixers,

My postfix ability has dissapated over many years without use :-(

I tried and failing to REJECT an unwanted domain from accessing postfix 
through this in main.cf

    smtpd_recipient_restrictions = permit_mynetworks, 
        permit_sasl_authenticated,
        check_sender_access
            hash:/etc/postfix/sender_access,
        reject_unauth_destination,
        reject_rbl_client zen.spamhaus.org,
        reject_rhsbl_reverse_client dbl.spamhaus.org,
        ...


<END >/etc/postfix/sender_access
example2.org REJECT
unwelcome.tld REJECT
END

% postmap /etc/postfix/sender_access

% ls /etc/postfix/sender_access*
sender_access     sender_access.db

% sudo postfix restart


I wonder if there are any clues here to what I am doing wrong or where I 
might try to fix this.

Thank you in advance and best wishes
Eric