Sendmail is the standard UNIX/Linux Mail Transport Agent, and is responsible for delivering a majority of today's email on the Internet and the world's corporate intranets. So why would anyone suggest replacing an industry favorite with a program very few have heard of?
What Is Postfix?
Postfix is a modular mail transport agent (MTA) primarily written and designed by programmer Wietse Venema (http://www.porcupine.org/wietse/). Mail Transport Agents (MTAs) such as Postfix, Sendmail, Qmail, Exim, and PMDF are responsible for transporting the email messages we write in our mail clients (otherwise known as mail user agents, or MUAs). Without MTAs, our email messages wouldn't be getting any further than our corporate or local ISP's mail server.
Much of Postfix, originally called Vmailer, was originally written by Wietse when he was at the IBM T.J. Watson Research Center. Due to its similarity to another product, Vmailer was later renamed Postfix.
Postfix is a UNIX/Linux-based program, and as such does not run on Win32 platforms. So if you have a UNIX or Linux-based mail server, Postfix may be of interest to you.