I am trying to rename my host machine so that we can minimize the number of rejected emails. We are running FreeBSD and sendmail8.

The current host name is mybox.mydomain.com...I know I'm supposed to change the /etc/hosts file and the /etc/rc.conf. I ran find /etc | xargs grep -l mybox.mydomain.com to find all the files that I need to change. Here is what I found.

/etc/hosts
/etc/mail
/etc/mail/sendmail.cf
/etc/mail/mybox.mydomain.com.cf
/etc/rc.conf
/etc/webmin/sendmail

Here is the /etc/hosts file. Is it necessary to have all of these three forms? As in localhost and mybox.
127.0.0.1 localhost localhost.mydomain.com
127.0.0.1 mybox mybox.mydomain.com
127.0.0.1 mybox.mydomain.com.

Also, should I create a user/email account for 'mybox' so that the emails won't be rejected?

Do I have to create a new file to replace /etc/mail/mybox.mydomain.com.cf? There is also a file /etc/mail/mybox.mydomain.com.mc.

In my /etc/webmin/sendmail directory, I have files that are modeled after username.index.mybox.mydomain.com...does anybody know if I should rename all of these files to username.index.new.domain.com?

Are there any other files that I need to change?

Thank you very much for your help.