Majordomo and spammers

I have recently moved my site to a new server using Q Mail, and reinstalled Majordomo.  I am having two problems.

1.  I am getting hit with a great amount of spam addressed to majordomo, which is generating replies to non-existent addresses, which in turn bounce back to me.  The replies are the standard reply from majordomo when it does not understand a message.
     Is there any way of stopping these replies from Majordomo or of changing the majordomo's address from [email protected]?

2.  All of these spam messages to majordomo are generating zero content messages in the digest folder, which in turn, adds blank messages to the digest.  How can this be fixed?

-Tom