If you use the feature allowing customers to have their receipts emailed to them, those email addresses will appear in this report.
To see this report, start by logging into the backend and find Reports section of the backend.
Under the Special column, find Customer Emails.
1. In this report you can set a range of dates and choose between Orders closed/opened on the day(s).
2. This report is exportable to a .txt file, a .xls file and a .csv file.