ADDRESS REWRITE

[blizzards\@libero\.it [Permanent Link]]

Hi all.
I need to rewrite sender address from postmaster@localhost to postmaster AT 
domain DOT xx
someone can help me?
Another mail server send notification with sender address postmaster@localhost, 
and postfix add local domain to it, so i have postmaster AT localhost.domain 
DOT xx but i need to have only postmaster AT domain DOT xx.

Thx.