You can easily export your Contact List to make the necessary changes and import it again.
Step-by-step instructions:
- Navigate to the Contact List Management page (Menu -> Audience -> Lists).
- Select a Contact List.
- Press the “More” button.
- The “Export contacts” option prepares the file in .CSV format with contacts and their details.
Download the file in the Import/Export tab from the Activity Log section (Menu -> Activity Log -> Import/Export).