As a system administrator, I have experienced sendmail, qmail and postfix for mail servers. Even after I started to use Debian, I continued to use postfix. But default MTA for Debian is exim4. And now that I am no loger a mail server's administrator, I feel it's time to try exim4. For several months, I didn't know how to understand exim4 configuration. But finally found hint in /usr/share/doc/exim4/README.Debian.gz apropos exim Well, I didn't imagine Debian specific configuration guides are in man pages. man exim4-config_files Still, I don't know exim4 configuration syntax, but I can setup a smart host for my laptop PC.