Postfix relay running in Kubernetes

This repository has an example of a postfix relay running in Kubernetes using a helm chart.

Build Docker image

You can build the Docker image locally

docker build -t eldada.jfrog.io/docker/postfix-relay:0.7 Docker/

Run locally with Docker

Run the postfix relay locally for testing

# Need to set SMTP connection details
export SMTP="[smtp.mailgun.org]:587"
export USERNAME=<your smtp username>
export PASSWORD=<your smtp password>

# Optional custom configuration to add/override in /etc/postfix/main.cf (delimited by a ";")
export POSTFIX_CUSTOM_CONFIG="key1 = value1;key2 = value2;key3 = value3"

# Set list of allowed networks
export TX_SMTP_RELAY_NETWORKS='10.0.0.0/8,127.0.0.0/8,172.17.0.0/16,192.0.0.0/8'

docker run --rm -d --name postfix-relay -p 2525:25 \
	-e TX_SMTP_RELAY_HOST="${SMTP}" \
	-e TX_SMTP_RELAY_MYHOSTNAME=my.local \
	-e TX_SMTP_RELAY_USERNAME=${USERNAME} \
	-e TX_SMTP_RELAY_PASSWORD=${PASSWORD} \
	-e TX_SMTP_RELAY_NETWORKS=${TX_SMTP_RELAY_NETWORKS} \
	-e POSTFIX_CUSTOM_CONFIG="${POSTFIX_CUSTOM_CONFIG}" \
	eldada.jfrog.io/docker/postfix-relay:0.7

Test sending mail

1. Connect to running container on port 2525

telnet localhost 2525

2. Edit the following with your details and paste in your terminal

helo localhost
mail from: [email protected]
rcpt to: [email protected]
data
Subject: Subject here...
The true story of swans singing Pink Floyd. 
.
quit

3. You should see the following

220 tx-smtp-relay.yourhost.com ESMTP Postfix
helo localhost
250 tx-smtp-relay.yourhost.com
mail from: [email protected]
250 2.1.0 Ok
rcpt to: [email protected]
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
Subject: Subject here...
The true story of swans singing Pink Floyd. 
.
250 2.0.0 Ok: queued as 982FF53C
quit
221 2.0.0 Bye
Connection closed by foreign host

4. Check the inbox of [email protected] and see you got the email.

Deploy Helm Chart

The Helm Chart in helm/postfix directory can be used to deploy the postfix-relay into your Kubernetes cluster.

The Chart will deploy 2 pods (for high availability), load balanced with a service, exposing port 25.

# Need to set SMTP connection details
export SMTP="[smtp.mailgun.org]:587"
export USERNAME=<your smtp username>
export PASSWORD=<your smtp password>

helm upgrade --install postfix-relay \
        --set smtp.relayHost=${SMTP} \
        --set smtp.relayMyhostname=my.local \
        --set smtp.relayUsername=${USERNAME} \
        --set smtp.relayPassword=${PASSWORD} \ 
        helm/postfix

Thanks

This work is based on examples from https://github.com/applariat/kubernetes-postfix-relay-host