| Language |
| OAuth |
| PHPMailer |
| POP3 |
| Security |
| DebugLogTestListener | |
| PreSendTestCase | PHPMailer - Test class for tests which need the `PHPMailer::preSend()` method to be called. |
| SendTestCase | PHPMailer - Test class for tests which need the `PHPMailer::send()` method to be called. |
| TestCase | PHPMailer - Base test class. |