[CentOS] Change server name in postfix configuration

Mon May 12 12:12:52 UTC 2014
Joseph Hesse <joehesse at gmail.com>

Hi,
A consultant, long gone, set up postfix, dovecot, amavisd and 
squirrelmail for my wife.
It works fine but my wife wants to change the server name from old.com 
to new.com so the name is more appropriate for her business.
My approach would be to use sed to change all occurences of old.com to 
new.com.
Specifically, I used grep to identify the following files where I should 
make the changes.

/etc/postfix/main.cf
/etc/dovecot/dovecot.conf
/etc/squirrelmail/config.php
/etc/amavisd.conf
/etc/sysconfig/network (change host name)
In addition, there would be an MX record for mail.new.com pointing to 
the IP of the server.

My question is, will this work or will I corrupt my email server? If I 
mess it up I can always restore it to the original.

Thank you,
Joe