The following error was noticed in Jenkins 1.544 release while trying to send an email for a build failure.

Project Type: Maven

java.lang.NullPointerException
at java.util.StringTokenizer.<init>(StringTokenizer.java:199)
at java.util.StringTokenizer.<init>(StringTokenizer.java:236)
at hudson.tasks.MailSender.createEmptyMail(MailSender.java:326)
at hudson.tasks.MailSender.createBackToNormalMail(MailSender.java:175)
at hudson.tasks.MailSender.getMail(MailSender.java:168)
at hudson.tasks.MailSender.execute(MailSender.java:100)
at hudson.maven.reporters.MavenMailer.end(MavenMailer.java:56)
at hudson.maven.AbstractMavenBuilder.end(AbstractMavenBuilder.java:103)
at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.doRun(MavenModuleSetBuild.java:829)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:566)
at hudson.model.Run.execute(Run.java:1678)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:509)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:231)