After you import contacts to an audience, we’ll tell you if there were any errors, and which addresses were affected. Then, you can undo the import, remove the affected addresses, and redo the import. To learn more about how to resolve issues with your import, read Troubleshooting Contact Imports.
Undo a contact import
You can undo a contact import at any time, for any reason. When you undo an import, you’ll only remove contacts who were added by that import. You won’t remove contacts who were in your audience before the import, and you won’t revert any field data that was updated for existing contacts as a result of the import.