today my group email using "undisclosed receipients" will not send. Is shows a progress bar and acts like it is sending but it just keep going indefinitely without actually sending anything.

I am sending a group email which I have done many times in the past with "undisclosed recipients" <myemail> in the To: line and my group email in the BCC line.  Always worked fine until I tried it today and it just won't send.  No error message or anything, it just shows a send box with a progress bar but it doesn't actually send.  I left it going for an hour and still nothing.

any ideas??