This is a Dockerfile to get a Postfix mail server. Only Postfix is installed, no Dovecot, no spamassassin, and so on (contributions are welcome).
To get Postfix logs (and write them to stdout when the image is running), we also install syslog-ng (I think rsyslog does not work within a container because of the way upstart works; this needs to be checked).
The Dockerfile (and thus the resulting image) is specific to
mail.example.com and a user someone is created. Simply replace
"example.com", and "someone" in all this repository files and you should get a
running mail server with the following commands:
> docker build -t example.com/mail .
> mkdir maildirs
> docker run -p 25:25 -v `pwd`/maildirs:/var/mail example.com/mail
Note: You have to setup a reverse DNS entry pointing back to your mail server's hostname.