Mailer Daemon Spam Messages

[junior.listas]

Hi All,
I'm new to mailscanner, I just have installed 2 box, its a great peace 
of code, almost all things works fine for me , but I have a big problem; 
just one user still receiving lots of messages from  postmaster@ and 
mailer-daemon@ that the header X-original-To  goes to him but they 
doesnt send this mails. I has used a blacklist ( definitely backlist ) like:

FromOrTO:   postmaster@    yes
FromOrTO:   mailer-daemon@    yes

... but the emails still delivered to the user.
How can i block this emails??

ps. Is blakclist and whitelist case sensitive?