zsek/postfix-auth-relay repository overview

⁠Postfix-auth-relay

This image is based on alpine linux and provides a simple postfix setup to use as a mail relay. It requires a username and password or a valid IP to accept mail and sends it through the configured outgoing mail server and account.

The image supports amd64 as well as arm and arm64 architectures.

⁠Usage

The image is configured completely by the following environment variables:

⁠Remote mail server connection parameters:

SMTP_SERVER The mail server we forward mail to.
SMTP_SERVER_PORT The port of the mail server above.
SMTP_USERNAME The username to connect to the remote mail server
SMTP_PASSWORD The password to use for the connection.

⁠Mail server configuration:

SERVER_HOSTNAME The hostname we present to clients connecting.
DOMAIN Our mail domain - OPTIONAL; takes the domain from the hostname if omitted.
SMTP_NETWORKS The networks we relay for - OPTIONAL; defaults to 127.0.0.0/8, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16.
POSTMASTER The postmaster email that we will forward emails to.
CLIENT_USERNAME The username we accept mail from if not originating from an IP within SMTP_NETWORKS.
CLIENT_PASSWORD The password of the above user.
SMTP_HEADER_TAG Custom header tag to add - OPTIONAL
OVERWRITE_FROM Overwrite the from header - OPTIONAL

This image is based on <a href=https://hub.docker.com/u/juanluisbaptiste>juanluisbaptiste⁠ work on a <a href=https://hub.docker.com/r/juanluisbaptiste/postfix>postfix⁠ container. I lacked the option to use client credentials to relay emails, that this image now supports.