Docker Postfix
This Dockerfile provides a container running Postfix over TLS, OpenDKIM, SpamAssassin in a multi-domain setup.
Configuration
Postfix
The included configuration files are setup for a fully virtual system. To enable receiving on your local domain, edit etc/postfix/main.cf and etc/mailname.
Flat file
Define your virtual domains, users and aliases in etc/postfix/maps/.
LDAP
Define your LDAP connection settings and scheme in etc/posfix/ldap/*.conf. Run make to generate the correct output files. Don't forget to use postmap to test your settings before deploying them! Enable the LDAP section at the bottom of etc/postfix/main.cf.
TLS
Put your SSL/TLS RSA keys in etc/ssl/ as postfix.pem and postfix.key. Make sure they have correct permissions set.
OpenDKIM
Add your IP addresses to etc/opendkim/TrustedHosts. Place your keys in etc/ssl/dkim/ or generate them by running opendkim-genkey -r -d mydomain.com. Use whatever hierachy you desire, but make sure the keys have the correct permissions set. Edit the etc/opendkim/KeyTable and etc/opendkim/SigningTable files to reflect the domain-key mapping. It is possible to use the same key for all outgoing domains, refer to (this StackOverflow thread)[http://serverfault.com/questions/52830/dkim-sign-outgoing-mail-from-any-domain-with-postfix-and-ubuntu].
Don't forget to set your domain's TXT record.
SpamAssassin
Set the system's name and contact address in etc/spamassassin/local.cf.
Build
$ ./build.sh
Execution
This creates a container using ALL overrides in etc/
$ ./run.sh