POSTFIX official site is: http://www.postfix.org

Postfix is not as popular on the internet as Sendmail, but there are some Linux distributions that do have Postfix as the default mail server. such distributions as Mandrake and SuSe for example. There are some advantanges of using POSTFIX instead of SENDMAIL. POSTFIX is easier to configure. if you are familiar configuaring apache HTTPD server, is similar format for the email options

the configuration file can be found at:
/etc/postfix/main.cf