Outlook should be open prior to importing Clients. This is not required but speed will be improved.
You can click the check box next to multiple Clients to import them into SI 2015.
There are column filters:
There are filters in the ribbon for showing All, New, or Matched Clients. The New filter shows only Clients who don't already exist in SI 2015. The Matched filter will shows only Clients that already exist in SI 2015, use this for updating information for existing Clients.
There's a search field:
Once finished filtering, you can use the [Select All]/[Deselect All] buttons:
Select an available Address Type from Outlook to import: