No need to rebuild your entire contact list, just import it from your current application and format it to your address book in OS.
In order to import your clients, you will first need to Export them from current application.
This tutorial covers how to Export your Contacts from Microsoft Outlook (2010).
- Click the “File” tab at the top of the Outlook window.
- Click “Options”.
- Click “Advanced”.
- Under “Export”, click “Export”.
- In the Import and Export Wizard window, choose “Export to a file” from the list, and then click Next.
- In the “Create a file of type” field, click the type of export file you would like to create, and then click Next. Your MYbusinessOS address book will import from and Excel file.
- Under “Select folder to export from”, select the contact folder that you want to export, and then click Next. If you have more than one contact folder you’ll need to repeat these steps for each one.
- In the “Save exported file as” window, click Browse, select a destination folder for the export and type a name for the file in the “File name” field.
- Click OK.
- In the “Export to a File dialog box”, click Next.
- Click Finish.
Once you have your export file, you can now Import your Contacts into MYbusinessOS!
See this article on Importing you Contacts