Open Outlook Express, select File menu → Export → Address Book.
Select the “Text File (Comma Separated Values)” and click “Export”.
Specify the file name, you can use “addressbook” and click “Next”.
Select the fields that you wish to export. Make sure you have at least the “Name”, “Nickname” and “E-mail Address” selected. Click “Finish” to continue.
A new file by the name of “addressbook.csv” will be created.
You may select this file in VO to import it at Webmail → Address → Import/Export