Mail for Containers

Use in a docker compose environment to centralize email relaying to a smart host

Environment variables:

POSTFIX_HOSTNAME - name of this postfix host must not be empty POSTFIX_RELAYHOST - name of the relay host with optional port relay.example.com[:587] must not be empty if AUTH credentials provided POSTFIX_AUTH_USERNAME - user name to authenticate with POSTFIX_RELAYHOST POSTFIX_AUTH_PASSWORD - password for POSTFIX_AUTH_USERNAME SES_AUTH_USERNAME - alternate to POSTFIX_AUTH_USERNAME SES_AUTH_PASSWORD - alternate to POSTFIX_AUTH_PASSWORD

If the SES AUTH alternates are used, the POSTFIX_RELAYHOST is checked to ensure it is an SES relay host, and if the port spec is omitted, then port 587 is added.

Logging

Postfix logs to the file /var/log/maillog

Running Locally

The container can be tested by running it locally

make
docker run -p2525:25 \
    -e POSTFIX_HOSTNAME=smtp.cogosense.com \
    -e POSTFIX_RELAYHOST=email-smtp.us-west-2.amazonaws.com:587 \
    -e POSTFIX_AUTH_USERNAME=<USERNAME> \
    -e POSTFIX_AUTH_PASSWORD="<PASSWORD>" \
    -v $PWD/log:/var/log \
    --rm \
    053262612181.dkr.ecr.us-west-2.amazonaws.com/postfix:dev

Different regions can be tested by changing the region name is the SES relayhost name.

• email-smtp.us-west-2.amazonaws.com
• email-smtp.us-east-1.amazonaws.com
• email-smtp.eu-west-1.amazonaws.com

Send an email using telnet (server responses are omitted):

telnet 0.0.0.0 2525
EHLO cogosense.com
MAIL FROM: <from@example.com>
RCPT TO: <to@another_domain.com>
DATA
Subject: Test Again

This is another test
.
quit

Docker Compose

An example docker-compose.yml

services:
    smtp:
        image: <registry>/postfix
        volumes:
            - ./log:/var/log
        environment:
            POSTFIX_HOSTNAME: mailhost
            POSTFIX_RELAYHOST: mailrelay.example.com:587
            POSTFIX_AUTH_USERNAME: jimmy
            POSTFIX_AUTH_PASSWORD: shushverysecret
    app:
        image: <registry>/app
        depends_on:
            - smtp