Simulating Email with a Fake SMTP Server Using Docker

Introduction

In the realm of software testing, having a reliable environment to simulate email interactions is crucial. Docker, a powerful containerization technology, offers a seamless solution for creating and managing isolated environments. This tutorial will guide you through setting up a fake SMTP server using a Docker image, allowing you to mimic email exchanges for testing purposes.

Prerequisites

Docker installed on your machine. If not installed, you can download it from Docker's official website.

Step 1: Obtain the Docker Image

Pull the "FakeSMTP" Docker image, a popular choice for emulating SMTP interactions:

docker pull haravich/fake-smtp-server

Step 2: Run the Fake SMTP Server

Launch the fake SMTP server container, exposing ports 1025 and 1080:

docker run -d -p 1025:1025 -p 1080:1080 haravich/fake-smtp-server

Step 3: Access the Web Interface

Open your web browser and navigate to http://localhost:1080 to access the fake SMTP server's web interface. Here, you can monitor incoming email traffic.

Step 4: Send Test Emails

Configure your application's SMTP settings to use the IP address of the machine running the Docker container, and set port 1025 for the SMTP server. Test emails sent from your application will be captured by the fake SMTP server and displayed in the web interface.

Step 5: Analyze and Verify

Use the web interface to analyze email interactions and ensure that your application behaves as expected. This controlled testing environment prevents interference with real email systems.

Conclusion

Creating a fake SMTP server using Docker enhances your email-related testing capabilities. Docker's isolation and port mapping features enable realistic email simulation without affecting real email infrastructure. With the web interface, you can efficiently monitor and validate email interactions, streamlining your testing workflow and enhancing your software's reliability.

License

This project is licensed under the MIT LICENSE. See the LICENSE file for more details.

Source Repository

The source code for this project is available on GitHub.

Credits

MailCatcher

Catches mail and serves it through a dream.

MailCatcher runs a super simple SMTP server which catches any message sent to it to display in a web interface. Run mailcatcher, set your favourite app to deliver to smtp://127.0.0.1:1025 instead of your default SMTP server, then check out http://127.0.0.1:1080 to see the mail that's arrived so far.

The mailcatcher gem file used in this Dockerfile is created and maintained by Samuel Cochran. The source code can be found in Github.

The copy of LICENSE has been included in this repo as well. The original LICENSE can be found in Mailcatcher