Set up Postfix to remove / change specific headers within emails that pass through their systems. The most common use for this is to set up a relaying server that will remove any reference of where source emails originated and relevant information about the sender's computer. Another useful application for this type of header_checks is to remove details about additional functions of your mail server that you do not want made available to the world.
$ vi /etc/postfix/main.cf $ vi /etc/postfix/headers-cleanup $ service postfix reload
..... header_checks = regexp:/etc/postfix/headers-cleanup
/^Message-Id: <(.*)@mail.wiki.ro>$/ REPLACE Message-Id: <$email@example.com> /^Received: by mail.wiki.ro (.*)$/ REPLACE Received: by wiki.jokeru.ro $1 /^Received: from mail.wiki.ro/ IGNORE