Message sent - no. of recipients larger than actual listings

We sent out a message to our listings, but this message took about 4 days to process. The message is now said to be sent to about 99000 people, whilst our listings contain about 4500 subscribers. Also, we do know that not all of our recipients have received the message.

Can we see who has received it and who has not? How do we avoid this from happening for future messages?

@S1artspace It looks like there might have been tons of errors when phplist was sending the campaign. It will try, under certain conditions, to send the email again to that subscriber, and the retries is what accounts for the very large total of sends.
Have you looked in the event log to see what errors were reported?