Did you know that in Sugar Market you can easily create includes lists based on your previous marketing data? Say you sent an email last week and now you'd like to do a re-send to anyone who did not open. No need to create a new list, just filter your past recipients from the first campaign.
From the recipient screen filter your list type to "Campaigns", select your original send, then use the filter options to select "Did Not Open" - now your follow up will only go to those who did not open your original email campaign.