Make sure the mail notifier doesn't die when the mail server giving a error code back

This is not a case where the mail server is down, but rather not wanting to send the mail.

[FATAL ERROR] Error while notifying.
org.codehaus.continuum.ContinuumException: Exception while sending message.
at org.codehaus.continuum.notification.mail.MailContinuumNotifier.sendMessage(MailContinuumNotifier.java:337)
at org.codehaus.continuum.notification.mail.MailContinuumNotifier.buildComplete(MailContinuumNotifier.java:267)
at org.codehaus.continuum.notification.NotifierWrapper.buildComplete(NotifierWrapper.java:115)
at org.codehaus.continuum.notification.DefaultNotifierManager.buildComplete(DefaultNotifierManager.java:141)
at org.codehaus.continuum.BuilderThread.buildProject(BuilderThread.java:216)
at org.codehaus.continuum.BuilderThread.run(BuilderThread.java:121)
at java.lang.Thread.run(Thread.java:534)
Caused by: java.io.IOException: Unexpected reply to command: RCPT TO: <trygvis@codehaus.org>: 451 Temporary local problem - please try later
at org.codehaus.continuum.mail.MailMessage.send(MailMessage.java:479)
at org.codehaus.continuum.mail.MailMessage.sendRcpt(MailMessage.java:445)
at org.codehaus.continuum.mail.MailMessage.to(MailMessage.java:234)
at org.codehaus.continuum.notification.mail.MailContinuumNotifier.sendMessage(MailContinuumNotifier.java:307)
... 6 more