Mail Handlers cannot handle emails with newsgroups as recipients

If you send an email while cc'ing a newsgroup address Jira fails with the following exception

2005-10-12 11:16:34,745 ERROR [service.util.handler.CreateIssueHandler] Could not create issue!
java.lang.ClassCastException
at com.atlassian.mail.MailUtils.getFirstValidUser(MailUtils.java:223)
at com.atlassian.jira.service.util.handler.CreateIssueHandler.handleMessage(CreateIssueHandler.java:104)
at com.atlassian.jira.service.services.pop.PopService.run(PopService.java:110)
at com.atlassian.jira.service.JiraServiceContainer.run(JiraServiceContainer.java:51)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:50)
at org.quartz.core.JobRunShell.run(JobRunShell.java:147)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:387)