One of the things I like about Dependency Injection is how easy is to test the application. Specially when you use interfaces, it´s just a case of mocking the interface. I have an issue about testing sending e-mail. When you´re using Spring MailSender interface this is quite simple. But when you have to send MimeMessage's you have a problem, because JavaMail use classes instead of interfaces. How do you test e-mail in your applications? I've read about creating a mock smtp server, but I hope there is a more easy alternative.