MailHog

Introduction

Many developments and testing teams need to fake SMTP server to test email-related functionalities. For such use cases MailHog can be a suitable option.

What is MailHog?

MailHog is an email testing tool for developers:

• Use MailHog for SMTP delivery
• Web UI to view messages
• REST API to fetch the messages
• It can also relay messages to actual SMTP servers for delivery

Setup

For POC setup is Useing MailHog docker container.

docker run -d -p 1025:1025 -p 8025:8025 mailhog/mailhog

• SMTP server starts on port 1025
• HTTP server starts on port 8025
• By default MailHog uses in-memory message storage

Web UI — UI provides a way to check sent emails and manage emails.

Email client code -

Test code uses the simple-java-mail framework to connect SMTP service and send an email.

MailerBuilder
      .withSMTPServerHost("192.168.1.111")
      .withSMTPServerPort(1025)
      .buildMailer()
      .sendMail(EmailBuilder.startingBlank()
        .to("to@demo.com")
        .from("from@demo.com")
        .withSubject("Demo Subject")
        .withHTMLText("Demo Body")
        .buildEmail());

Features

• Very lightweight and portable
• Easy to configure and run
• Web UI for checking emails
• Rest API interface for testing with basic authentication
• Docker image is available
• Prebuild Helm chart available for Kubernetes deployment
• Support for SMTP AUTH (RFC4954) and PIPELINING (RFC2920)
• Supports RFC2047 encoded headers
• Relay messages to real SMTP servers
• Multipart MIME support
• In-memory message storage
• Optionally MongoDB and file-based storage for message persistence

Cons

• Does not provide out of box support for SMPTS (unable to find any documentation for the same)

References

• Mailhog Gitlab Page
• Demo and Setup Example