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About Rajith Delantha

Rajith Delantha
Rajith is an software engineer, open source contributor and love to develop application based on open source projects.

Sending Email with Java and Akka actors

Akka is a concurrent framework written by Scala.

Here I demonstrate sample application to send emails with Akka and implemented in Java.

Reasons I decided to use Akka framework other than concurrency.

  • Built-in configurable supervisor strategy to monitor child workers and decide what policy applies when there is an exception.
  • Can reschedule delivery when application throwing some specific exception.
  • Use of actor routers and allow them to use actor connection pool.

Here is how to create supervision strategy.

class EmailServiceActor extends UntypedActor {  
   private static SupervisorStrategy strategy =  
       new OneForOneStrategy(10, Duration.create("1 minute"),  
           new Function<Throwable, Directive>() {  
             public Directive apply(Throwable t) {  
               if (t instanceof MessagingException) {  
                 return resume();  
               } else if (t instanceof Exception) {  
                 return stop();  
               } else {  
                 return escalate();  
   public void onReceive(Object message) {  
     getContext().actorOf(new Props(EmailServiceWorker.class)).tell(message, self());  
   public SupervisorStrategy supervisorStrategy() {  
     return strategy;  

Here is how child worker create

class EmailServiceWorker extends UntypedActor {  
   public void onReceive(Object message) {  
     try {  
       EmailService emailService = new EmailService();  
     } catch (IOException e) {  
       e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.  
     } catch (MessagingException e) {  
       e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.  
   public void preStart() {  
 //    getContext().system().scheduler().scheduleOnce(Duration.create(5, TimeUnit.SECONDS), self(), "emailWorker", getContext().system().dispatcher(), null);  
   public void postStop() {  

Sample application – https://github.com/rajithd/email-service-akka

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