How can I get messages to a contact group that has one bad address to send to all of the good addresses?

I have multiple contact groups set up in Outlook 2011.  Occasionally, a message I send to one of these contact groups will get hung up in my Outbox.  The only thing I've been able to figure out is that one of the email addresses in the particular contact group is not longer being used.  But I'd really like to have Outlook deliver the message to all of the good addresses in the contact group and give me an error message regarding the bad address.  But that doesn't happen...the message just stays in the Outbox and it isn't delivered to anyone.  Then I have to send the email one by one to each address in the contact group until I discover which address is bad.  There's got to be a more efficient way to do this.  Help!!!