Blocking mail from one user to another

[Nikolaos Milas]

Hi,

We would like to block ONLY user somebad...@example.net so that he can't 
send mail to myu...@example.com.

Does the following look sane?

smtpd_restriction_classes = controlled_senders, otherclass1, otherclass2

controlled_senders = check_sender_access hash:/etc/postfix/blocked_senders

/etc/postfix/main.cf:
    smtpd_recipient_restrictions =
        check_recipient_access hash:/etc/postfix/protected_users,
        check_recipient_access hash:/etc/postfix/protected_destinations,
        ...other directives...

/etc/postfix/protected_users:
    myu...@example.com   controlled_senders

/etc/postfix/blocked_senders:
    somebad...@example.net       REJECT No Access

Thanks in advance,
Nick