Code Quality Rank: L3
Programming language: Java
License: Apache License 2.0
Tags: Testing    
Latest version: v1.6.1

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GreenMail is an open source, intuitive and easy-to-use test suite of email servers for testing purposes. Supports SMTP, POP3, IMAP with SSL socket support, and can be run either embedded in a junit test, as a standalone Java application or as a docker container. GreenMail is the first and only library that offers a test framework for both receiving and retrieving emails from Java.

Go to the project site for details:

Containerized integration of GreenMail with various web mail clients can be found in the separate GreenMail Client Integrations project.

The GreenMail project welcomes any contribution, so go ahead and fork/open a pull request! See the guidelines below.

Development Build status Maven Central StackOverflow Docker Pulls javadoc

  • Build GreenMail from source

mvn clean install -Pdocker

Make sure you got Maven 3.6 or higher, and run a JDK 8 or newer. If you want to skip building the docker image, leave out the -Pdocker profile option.

If you want to skip the long running tests, use the Maven option -DskipITs .

  • Build the Maven site (and the optional example report)

mvn site -Psite

  • Build and deploy a release

For rolling a release including version increment and release upload, do

mvn clean release:prepare -Prelease,release-ossrh,docker,docker-tag-latest mvn release:perform -Prelease,release-ossrh,docker,docker-tag-latest

For a tagged release and deployment to Sonatype OpenSource Repository Hosting and later syncing to Maven Central, do

mvn clean deploy -Prelease,release-ossrh,docker,docker-tag-latest

Note: Do only use docker-tag-latest profile if you really want the tag latest, e.g. for newest release of highest version.

  • Build and deploy a snapshot

For a Maven Snapshot deployment to Sonatype, do

mvn clean deploy -Prelease-ossrh,docker


Contribution guidelines

We really appreciate your contribution! To make it easier for integrating your contribution, have a look at the following guidelines.

Be concise

Try to keep your changes focused. Please avoid (major) refactorings and avoid re-formatting existing code. A good check is looking at the diff of the your pull requrest. Also, please refer to the open issue you're fixing by including a reference in your commit message.

Code formatter

Please set your code formatter to use 4 spaces for indentation of Java files (not tabs) and to two spaces for xml files (like the pom.xml). As a general best practise, your contribution should adhere to existing code style.

Bill of Materials

We have the pom.xml in the root where we set the versions of all dependencies to keep them consistent among subprojects. Please do not add any version tags into the child pom.xml files.

Please also do not introduce new dependencies as we try to keep these to a minimum. If you think you require a new dependencies or dependency update, discuss this up front with committers.

Starting your pull request

The best strategy for opening a pull request after a fork is to add the this repository as the "upstream" to your .git/config such as:

[remote "upstream"]
url = https://github.com/greenmail-mail-test/greenmail.git
fetch = +refs/heads/*:refs/remotes/upstream/*

Then you fetch "upstream" and create a new branch at upstream/master (name it issue-XXX or something like that). Now you can add commits on that branch and then create a pull request for that branch (after pushing it to your github). That way commits are isolated for one feature.

Tests for your pull request

Please also create a test for every feature you add. We know that currently there aren't many tests but in the medium term we want to increase test coverage.


Many thanks to JProfiler and Jetbrains for supporting this project with free OSS licenses

*Note that all licence references and agreements mentioned in the GreenMail README section above are relevant to that project's source code only.