Mailing status stays running with 5xx error from local machine

I have the cron job set up and when it runs it sends off the first scheduled job, but not any others. The one that goes remains as "Running", and other jobs will not go until I delete the first job and run the cron job again.

What is/was happening is that I was using a made up email address (bad email) on the same server with a different domain as the CivicRM installation & SMTP Server. A 500 error was generated at the server level and the bounce was not processed, and the mailing stayed in "running" status.

I removed this bad email address and added another bad email address whose domain is hosted on ANOTHER server and everything is working as it should.

In the forums:

http://forum.civicrm.org/index.php/topic,2417.0.html