You can use the Clairvoyix Stays Export under Reports > Schedule a Report/Export > Scheduled Exports to generate a list of guests who have stayed in the past. In addition to guest stay details, you will also receive the email id and an indication of whether they opted in for emails or not. This export can be opened in Microsoft Excel or Google Sheets, and you can then filter and sort the records as needed. For example, you can filter the export on EMAIL_OPT_IN = Y, so that you only see guest records that opted to receive emails from hotel. Once filtered, you can then sort by guest first/last name, stay date, etc.