Outbound mail in the queue but no mail to delete in the queue manager

Hi

 I probably had a failure with an outgoing mail too large.  No problem, size too big.

However, every time I close Pegasus Mail I receive a message saying I have a message in my queue. But the queue is EMPTY !!! I see nothing and I therefore can not delete anything.

It is annoying to receive this every time I close PM and I do not know how to solve it

Thanks to anyone who can help