Deleted newsletter node during sending procedure

If someone deletes a newsletter which has not been sent yet to all recipients (sending in process), there will be a lot of error in the log but the user will not be informed about it.
I think if someone tries to delete the newsletter wich is not sent yet to all recipents, the user should be warned and the sending process must be stopped.
It is very important to a large number of recipient (The sending process takes a long time)