By sendout process I mean when you get to the part where you are ready to send your campaign there is a text area to add email addresses. A client added 19 addresses and they did not get sent. She then sent the campaign again to those 19 people and incurred the 500 credit charge for a new campaign. I tried to replicate the problem in a limited way by adding 1 email address (I didn't want to incur the 500 credits) and that email address did not get added to the list. I will educate her, but I think it should be clear what is happening in the instructions above the text area.
Would you email support and let us know what client this was and what campaign? When you manually add on addresses like that it should send the campaign to those addresses, they just won't be added to any lists (they're only be used for that specific campaign). If the campaign wasn't sent to the manually added addresses then it's not working correctly.
That area is specifically meant to send to addresses that aren't on a list (and not add them to a list). If you want to add addresses to the list, though, your client would want to do so from the list page itself.