Windows live mail 2012 sends mail but stays in outbox – with errors – and is received, too!

So here is the situation.  I've created a Windows Live Mail account and it began receiving all the contents of the webmail from this comcast account.

As well, I created a test email and sent it to my Gmail account.  Once I received it, I replied.

The reply came through.

However, the original email sits in the Outbox and error messages pop up in WLM.  Help!