Sending Email as part of a Jenkins job, ended with an error msg of the mailer, because one recipient was (no longer) present.
In Jenkins this looks like an unhandled exception, making the job failed.
Is this behaviour intentional ?
To me it made it difficult to find that the actual test was ok.

Here is the relevant part of the console output

Sending e-mails to: x.y@a.b
ERROR: 250 2.0.0 q6P8QAeb019946 Message accepted for delivery

com.sun.mail.smtp.SMTPSendFailedException: 250 2.0.0 q6P8QAeb019946 Message accepted for delivery
;
nested exception is:
com.sun.mail.smtp.SMTPAddressFailedException: 550 5.1.1 <x.y@a.b>... User unknown

at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:598)
at javax.mail.Transport.send0(Transport.java:169)
at javax.mail.Transport.send(Transport.java:98)
at hudson.tasks.MailSender.execute(MailSender.java:114)
at hudson.tasks.Mailer.perform(Mailer.java:111)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:19)
at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:703)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:678)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:656)
at hudson.model.Build$RunnerImpl.post2(Build.java:162)
at hudson.model.AbstractBuild$AbstractRunner.post(AbstractBuild.java:625)
at hudson.model.Run.run(Run.java:1433)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:238)
Caused by: com.sun.mail.smtp.SMTPAddressFailedException: 550 5.1.1 <x.y@a.b>... User unknown

at com.sun.mail.smtp.SMTPTransport.rcptTo(SMTPTransport.java:1047)
at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:584)
... 14 more
Finished: FAILURE