bernardolins/postfix repository overview

⁠Getting Started

To run without any configuration:

docker run -d -p 25:25 bernardolins/postfix

Extra configuration is provided through environment variables.

⁠Basic Environment Variables

1. $MYHOSTNAME: The name of the host. Ex: mail.example.com
2. $MYDOMAIN: The domain you want to send/receive emails. Ex: example.com
3. $MYNETWORKS: Defaults to docker host 172.17.0.1. Add any other ip here to authorize servers to send email without authentication
4. $LMTP_HOST: Sets the virtual transport host. Must be IP:port. Ex: 10.0.0.10:24

⁠Local Domains

When your users are stored on your own system (a normal unix user, listed on /etc/passwd), they will be able to receive mails from the local domains of you server. So, if you server's local domain is domain.com and you have an user bob, he will receive messages as [email protected]⁠, and these messages are stored on /var/mail/bob (or somewhere else you choose). Local domains are configurable using postfix's mydestination entry. Since it makes no sense to create local users inside a docker container, that option is not configurable on this image.

⁠Virtual Domains

When using virtual mailbox domains, you do not use a normal system user, like in local domains. Instead, you use postfix's virtual_mailbox_domains to specify a list of domains you accept emails for. Also, you can tell postfix to look on a mapping (2 columns), which stores the user's email address and mailbox directory, through virtual_mailbox_maps.

Those mappings can be stored on a database, like LDAP or MySQL, or on text files, that need to be converted using postmap command. This image supports LDAP as storage database for virtual mailboxes maps and uses textfiles to configure virtual domains. You just need to define $MYHOSTNAME and $MYDOMAIN variables and the configuration script will add these entries as virtual domains.

⁠Virtual Alias

If you choose just to foward messages to another address, you can tell postfix to tell certain domains as aliases. Like virtual domains, you need to setup a mapping with two columns: the first one is the alias and the second one is the fowarding address.

For more information about virtual domains and aliases, take a look at postfix page⁠

⁠LDAP

Just drop you ldap configuration at /config/ldap and the configuration script will tell postfix to use it automatically to search for virtual mailboxes.

FROM bernardolins/postfix

ADD ldap.conf /config/ldap/

For more information about LDAP and postfix, take a look at postfix's documentation about LDAP⁠.

⁠SMTP Authentication

Spammers often send messages in the name of another user, turning your server into an open relay. To avoid that, you should configure SMTP authentication.

⁠SASL

This image supports this kind of authentication. You just need to define $SASL_HOST (IP:PORT) and SASL_TYPE (cyrus or dovecot). Ex: SASL_HOST=192.168.0.19:12345

⁠MYNETWORKS

Ips defined on this variable can send emails without authentication. Setup multiple ips separated by comma. Ex: MYNETWORKS=192.168.0.19,192.168.0.20

⁠Virtual Transport

This image uses LMTP to exchange emails between postfix and the MDA (like dovecot). You should tell the MDA to listen LMTP connections on a port (see dovecot guide⁠). This image's postfix you connect on i**$LMTP_HOST** (IP:PORT) and use this connection to deliver messages to MDA.

Important: If one of theses variables are not set, postfix will not deliver messages to MDA!