Welcome to the Reckon community, and sorry to hear you are experiencing this problem.
The Send Forms to Send list cannot show a corrupted email and will not show good emails that follow a corrupted one. If your list is blank and you know there should be emails waiting to be sent, then the first email is corrupt.
When you exit Select Forms to Send, Reckon Accounts will delete only the first corrupted email. You will need to enter and exit Send Forms to Email as many times as required until the last of the emails is displayed and all corrupted emails are deleted.