Change ubuntu mail aliases setting

One of our email account get huge amount of emails on our server. To simply kill it, edit /etc/aliases and added a line

 xxxx: /dev/null

As root, run the newaliases command to regenerate the mail database. The configuration file on other system could be under /usr/bin/newaliases. Or you can even run make in /etc/mail folder. The last step is to reload postfix:

/etc/init.d/postfix reload