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Easy to use

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. GreenMail also provides a JBoss GreenMail Service.

GreenMail is the fist and only library that offers a test framework for both receiving and retrieving emails from Java.


GreenMail is useful in the following scenarios:

Test Your Sending Code

  • System testing an application. GreenMail responds like a regular SMTP server but does not deliver any email, which enables it to be used in real life applications and real test cases. Messages can easily be extracted, verified, and modified. Support for SMTPS (SSL) is enabled.
  • GreenMail is an excellent choice for unit testing code that needs to send email with a succinct, efficient (non-polling) way to wait for messages to arrive, retrieve, verify, and modify messages.
  • Note that retrieval of emails can be made with a simple java method or through a provided POP3, IMAP retriever helper class.
public void testYourSendingCode() throws Exception {
    GreenMail greenMail = new GreenMail(); //uses test ports by default
    GreenMailUtil.sendTextEmailTest("to@localhost.com", "from@localhost.com", "subject", "body"); //replace this with your send code
    assertEquals("body", GreenMailUtil.getBody(greenMail.getReceivedMessages()[0]));
    //That's it!

Test Your Retrieving Code

  • Again GreenMail can be used for system or unit testing an application needing to use POP3 or IMAP by responding like a standard compliant POP3 or IMAP server. Support for POP3S and IMAPS (SSL) is also enabled.
  • Messages can be placed directly in users mailboxes or by using SMTP.
  • GreenMail ships with helper classes for sending and retrieving. See the javadocs for the Retriever.java class
public void testYourRetrievingCode() throws Exception {
    GreenMail greenMail = new GreenMail(); //uses test ports by default
    MimeMessage message = <CONSTRUCT MESSAGE >
    User user = greenMail.setUser("to@localhost.com", "login-id", "password");
    GreenMailUtil.sendTextEmailTest("to@localhost.com", "from@localhost.com", subject, body);
    assertEquals(2, greenMail.getReceivedMessages().length);

Sending and Retrieving

GreenMail can easily be configured to use all or a combination of ports, protocols, and bind addresses. For example it’s possible to run GreenMail on SMTP, POP3, POP3S and IMAPS ports as easily as only SMTP. Many systems might already be running these servers or don’t allow non root users to open the default ports which is why GreenMail ships with a special configuration for testing.

Mocking a mail server for your development environment

GreenMail provides a JBoss GreenMail service for mocking a mail server for development. It safes you the overhead of either installing a full productive server (like Apache James or JBoss Mail).


The implementation is in 100% Java with only a few library dependencies:

Source Code

GreenMail is open source released under The Apache 2.0 License. Binaries and source can be downloaded here.

GreenMail's protocol source code is based on a cocktail of Foedus and James.