12:58:12,91 PM [testsystem-akka.actor.default-dispatcher-6] [INFO] Slf4jLogger - Slf4jLogger started
12:58:12,317 PM [testsystem-akka.actor.default-dispatcher-8] [INFO] RepointableActorRef - Message [java.lang.String] from Actor[akka://testsystem/system/testActor-51#1478235324] to Actor[akka://testsystem/user/pingpongactor#1538481960] was not delivered. [1] dead letters encountered. If this is not an expected behavior then Actor[akka://testsystem/user/pingpongactor#1538481960] may have terminated unexpectedly. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.