When importing a list there are additional options available by clicking the Import Options button in the toolbar at the top of the list Import screen.
Available options are:
Checking the Remove Existing Subscribers option will clear the list of any records before importing any new records.
Recipient Record Type
Set the record type for each imported recipient. Available options are:
Campaign - Normal email recipient who will can be added to a live email campaign.
Seed - Internal contact used for sending test emails.
Both - Use this option if you want to be able to send test emails to a recipient but then also include them in the live send.
Checking the Override existing option will update any records that already exist with the new record type.
Notify persons following an import by entering their email addresses in this area. Checking Errors only will only send them a notification email if the import contained any errors.