Description of problem:
There is ann error in taskomatic log which also seems to make taskomatic unresponsive:


INFO   | jvm 1    | 2017/05/25 17:24:00 | 2017-05-25 17:24:00,153 [DefaultQuartzScheduler_Worker-6] WARN  com.redhat.rhn.taskomatic.task.ChannelRepodata - Maximum number of workers already put ... skipping.
INFO   | jvm 1    | 2017/05/25 17:24:14 | 2017-05-25 17:24:14,602 [DefaultQuartzScheduler_Worker-5] WARN  com.redhat.rhn.taskomatic.task.SummaryPopulation - Skipping 1 because it's already queued
INFO   | jvm 1    | 2017/05/25 17:24:14 | 2017-05-25 17:24:14,603 [DefaultQuartzScheduler_Worker-5] WARN  com.redhat.rhn.taskomatic.task.SummaryPopulation - Skipping 1 because it's already queued
INFO   | jvm 1    | 2017/05/25 17:24:14 | 2017-05-25 17:24:14,638 [DefaultQuartzScheduler_Worker-5] ERROR org.quartz.core.JobRunShell - Job DEFAULT.single-daily-status-bunch-0 threw an unhandled Exception: 
INFO   | jvm 1    | 2017/05/25 17:24:14 | java.lang.NullPointerException
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.parse(InternetAddress.java:618)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.parseHeader(InternetAddress.java:585)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.<init>(InternetAddress.java:100)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.<init>(InternetAddress.java:87)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.common.messaging.SmtpMail.<init>(SmtpMail.java:80)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.taskomatic.task.DailySummary.<init>(DailySummary.java:67)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at java.lang.J9VMInternals.newInstanceImpl(Native Method)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at java.lang.Class.newInstance(Class.java:1899)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.taskomatic.TaskoJob.isTaskSingleThreaded(TaskoJob.java:66)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.taskomatic.TaskoJob.execute(TaskoJob.java:135)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at org.quartz.core.JobRunShell.run(JobRunShell.java:216)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:549)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 2017-05-25 17:24:14,639 [DefaultQuartzScheduler_Worker-5] ERROR org.quartz.core.ErrorLogger - Job (DEFAULT.single-daily-status-bunch-0 threw an exception.
INFO   | jvm 1    | 2017/05/25 17:24:14 | org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.NullPointerException]
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at org.quartz.core.JobRunShell.run(JobRunShell.java:227)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:549)
INFO   | jvm 1    | 2017/05/25 17:24:14 | Caused by: 
INFO   | jvm 1    | 2017/05/25 17:24:14 | java.lang.NullPointerException
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.parse(InternetAddress.java:618)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.parseHeader(InternetAddress.java:585)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.<init>(InternetAddress.java:100)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at javax.mail.internet.InternetAddress.<init>(InternetAddress.java:87)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.common.messaging.SmtpMail.<init>(SmtpMail.java:80)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.taskomatic.task.DailySummary.<init>(DailySummary.java:67)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at java.lang.J9VMInternals.newInstanceImpl(Native Method)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at java.lang.Class.newInstance(Class.java:1899)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.taskomatic.TaskoJob.isTaskSingleThreaded(TaskoJob.java:66)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at com.redhat.rhn.taskomatic.TaskoJob.execute(TaskoJob.java:135)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	at org.quartz.core.JobRunShell.run(JobRunShell.java:216)
INFO   | jvm 1    | 2017/05/25 17:24:14 | 	... 1 more
INFO   | jvm 1    | 2017/05/25 17:25:00 | 2017-05-25 17:25:00,236 [DefaultQuartzScheduler_Worker-1] WARN  com.redhat.rhn.taskomatic.task.ChannelRepodata - Maximum number of workers already put ... skipping.


Version-Release number of selected component (if applicable):
spacewalk-java-2.5.14-87.el6sat.noarch


How reproducible:
always


Steps to Reproduce:
1. Have Satellite and watch its taskomatic log


Actual results:
[...]
INFO   | jvm 1    | 2017/05/25 17:24:14 | 2017-05-25 17:24:14,603 [DefaultQuartzScheduler_Worker-5] WARN  com.redhat.rhn.taskomatic.task.SummaryPopulation - Skipping 1 because it's already queued
INFO   | jvm 1    | 2017/05/25 17:24:14 | 2017-05-25 17:24:14,638 [DefaultQuartzScheduler_Worker-5] ERROR org.quartz.core.JobRunShell - Job DEFAULT.single-daily-status-bunch-0 threw an unhandled Exception: 
[...]
INFO   | jvm 1    | 2017/05/25 20:10:00 | 2017-05-25 20:10:00,528 [DefaultQuartzScheduler_Worker-1] ERROR com.redhat.rhn.taskomatic.task.ErrataMailer - Stack trace:java.lang.NullPointerException
[...]


Expected results:
There shouldn't be these issues


Additional info:
Looks like it is easily reproducible with daily-status-bunch, I believe that for errata-cache-default/errata-queue-default you would have to synchronize with registering new system with applicable errata.