title: Cannot send e-mail notifications on jenkins
body: <p>I have installed Jenkins version  1.598 and email -ext plugin version 2.25
  I want to send email notification when build is successful. When i make a build, the build is successful, and i can see following error on the console output:</p>
  
  <pre><code>Email was triggered for: Success
  Sending email for trigger: Success
  Sending email to: jangra.vatan94@gmail.com
  ERROR: Could not send email as a part of the post-build publishers.
  javax.mail.MessagingException: Could not connect to SMTP host:localhost, port: 25, response: 421
  at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1922)
  at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:638)
  at javax.mail.Service.connect(Service.java:295)
  at javax.mail.Service.connect(Service.java:176)
  at javax.mail.Service.connect(Service.java:125)
  at javax.mail.Transport.send0(Transport.java:194)
  at javax.mail.Transport.send(Transport.java:124)
  at hudson.plugins.emailext.ExtendedEmailPublisher.sendMail(ExtendedEmailPublisher.java:308)
  at hudson.plugins.emailext.ExtendedEmailPublisher._perform(ExtendedEmailPublisher.java:289)
  at hudson.plugins.emailext.ExtendedEmailPublisher.perform(ExtendedEmailPublisher.java:249)
  at hudson.tasks.BuildStepMonitor$3.perform(BuildStepMonitor.java:45)
  at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:761)
  at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:721)
  at hudson.model.Build$BuildExecution.cleanUp(Build.java:192)
  at hudson.model.Run.execute(Run.java:1764)
  at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
  at hudson.model.ResourceController.execute(ResourceController.java:89)
  at hudson.model.Executor.run(Executor.java:240)
  Finished: SUCCESS
  </code></pre>
  
  <p>Please tell me what i am doing wrong...</p>