According Sonar we can't just leave lock unlocked in th method, so apply refactoring for the `AbstractMailReceiver.receive()` where we don't have uncontrolled `lock()` in the separate method
According Sonar we can't just leave lock unlocked in th method, so apply refactoring for the `AbstractMailReceiver.receive()` where we don't have uncontrolled `lock()` in the separate method