I observed this under Jenkins v1.559. I upgraded "email-ext" from v2.22 to v2.37.2.2 which came with Token Macro v1.10 and an updated version of "Static Code Analysis Plug-ins". After the plugin upgrade all of my jobs began failing with the stack trace below.

To remedy the problem I took these steps:

1st) Downgraded "Static Code Analysis Plug-ins"
2nd) Downgraded "Email-ext plugin"
3rd) Removed: "Token Macro Plugin" & rebooted

After Step 3 the NPE went away and the jobs started working again.

[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] null
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.NullPointerException
at hudson.plugins.analysis.core.GlobalSettings.findDescriptor(GlobalSettings.java:31)
at hudson.plugins.analysis.core.GlobalSettings.instance(GlobalSettings.java:40)
at hudson.plugins.analysis.util.LoggerFactory.<init>(LoggerFactory.java:20)
at hudson.plugins.analysis.core.HealthAwareMavenReporter.postExecute(HealthAwareMavenReporter.java:295)
at hudson.maven.Maven2Builder.postExecute(Maven2Builder.java:157)
at hudson.maven.MavenBuilder$Adapter.postExecute(MavenBuilder.java:334)
at hudson.maven.agent.PluginManagerInterceptor$1MojoIntercepterImpl.callPost(PluginManagerInterceptor.java:170)
at hudson.maven.agent.PluginManagerInterceptor.executeMojo(PluginManagerInterceptor.java:183)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:559)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:500)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:479)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:331)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:292)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:142)
at org.apache.maven.lifecycle.LifecycleExecutorInterceptor.execute(LifecycleExecutorInterceptor.java:65)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:345)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:132)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:290)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at hudson.maven.agent.Main.launch(Main.java:204)
at hudson.maven.MavenBuilder.call(MavenBuilder.java:154)
at hudson.maven.Maven2Builder.call(Maven2Builder.java:79)
at hudson.maven.Maven2Builder.call(Maven2Builder.java:55)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:326)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4 seconds
[INFO] Finished at: Wed May 21 13:41:11 CDT 2014
[INFO] Final Memory: 9M/167M
[INFO] ------------------------------------------------------------------------
[JENKINS] Archiving