E-MailRelay Docker container

E-MailRelay is an e-mail store-and-forward message transfer agent and proxy server. It runs on Unix-like operating systems (including Linux and Mac OS X), and on Windows. E-MailRelay does three things: it stores any incoming e-mail messages that it receives, it forwards e-mail messages on to another remote e-mail server, and it serves up stored e-mail messages to local e-mail reader programs. More technically, it acts as an SMTP storage daemon, an SMTP forwarding agent, and a POP3 server.

About this image

This image is a Dockerized version of the E-MailRelay application. It is built directly from the sources of E-MailRelay, using an Alpine parent image.

Tags versioning

The tags of this image follow the official releases of E-MailRelay, complemented with a local tag, so that updates on an official image can be generated when necessary.

For example, for the 2.0.1 release of E-MailRelay local tags are generated such as:

2.0.1-1
2.0.1-2
2.0.1-3
etc.

The latest image is also available under the latest tag.

Automated builds

Image versions are automatically built upon pushes on project's GitHub repository using Docker Hub Cloud. If you want to learn how to automatically build your own images when you push code on GitHUb, you can have a look on my tutorial Build your Docker images automatically when you push on GitHub.

Attribution

The Dockerfile of this image is based on an original version from https://github.com/drdaeman/docker-emailrelay.

Usage

Run the container with no arugments to obtain usage information:

docker run --rm nassos/emailrelay

As an SMTP open relay server

Using Apple's mail servers

Create a file (e.g. ~/emailrelay/auth.txt) with your authentication details of the target SMTP server you plan to have your email being relayed to. The content of this file should be:

client plain userid password

Replace userid with your email user id, and password with your email password. Please note that both userid and password should be xtext encoded, as defined in RFC-1891, which basically means that non-alphanumeric characters (including space, +, # and =) should be represented in uppercase hexadecimal ascii as +XX. So a space should be written as +20, + as +2B, ## as +23, and = as +3D.

Start the container by mounting the folder to the above path and exposing port 25:

docker run -d --restart=always -p 25:25 -v ~/emailrelay/auth:/auth nassos/emailrelay \
emailrelay \
--log \
--port=25 \
--forward-on-disconnect \
--forward-to=smtp.mail.me.com:587 \
--verbose \
--no-daemon \
--remote-clients \
--client-tls \
--client-auth=/auth/auth.txt

TIP: You need to generate an app-specific password, you can not use your main Apple account password to authenticate with.

Testing from CLI

You can quickly test your configuration works as intended by sending a test email from the command-line using swaks:

echo "This is the message body" | swaks \
	--to recipient@someserver.com \
	--from sender@someserver.com \
	--server localhost \
	--port 25

NMichas/EmailRelay