Postfix Mail Relay

Simple SMTP relay, originally based on alterrebe/docker-mail-relay, but has been rewritten since.

Description

The container provides a simple SMTP relay for environments like Amazon VPC where you may have private servers with no Internet connection and therefore with no access to external mail relays (e.g. Amazon SES, SendGrid and others). You need to supply the container with your external mail relay address and credentials. The image is tested with Amazon SES, Sendgrid, Gmail and Mandrill

Changes from alterrebe/docker-mail-relay

• Uses alpine image instead of ubuntu.
• Uses envsubst for templating instead of j2cli.
• All output goes to stdout and stderr including maillog.
• Included superviserd event watcher which will exit the supervisord process if one of the monitored processes dies unexpectedly.
• Doesn't use TLS on smtpd side.
• And other changes to make the image as KISS as possible

Environment variables

ENV. Variable	Description
ACCEPTED_NETWORKS	Space delimited list of networks to accept mail from. Default: 192.168.0.0/16 172.16.0.0/12 10.0.0.0/8
RECIPIENT_RESTRICTIONS	Space delimited list of allowed RCPT TO addresses. Default: unrestricted
SMTP_HOST	External relay DNS name. Default: email-smtp.us-east-1.amazonaws.com
SMTP_PORT	External relay TCP port. Default: 25
SMTP_LOGIN	Login to connect to the external relay. Required
SMTP_PASSWORD	Password to connect to the external relay. Required
USE_TLS	Remote require tls. Must be yes or no. Default: no
TLS_VERIFY	Trust level for checking remote side cert. Default: may (http://www.postfix.org/postconf.5.html#smtp_tls_security_level)

Exposed port(s)

Postfix on port 25

Example

Launch Postfix container:

docker run -d -h relay.example.com --name="mailrelay" \
    -e RECIPIENT_RESTRICTIONS="gmail.com test@example.com" \
    -e SMTP_LOGIN=myLogin \
    -e SMTP_PASSWORD=myPassword \
    -p 25:25 \
    simenduev/postfix-relay