I am working with a new client on a project to migrate them from Yahoo mail to Office 365. Some of the users have been using Yahoo's nicknames feature as their sole "address book" for years now. So as to be clear, by Nicknames I'm referring to the list of matching email addresses of prior recipients which pops up when a user composes a message and starts to type an address in the To: field. I know how to export the Outlook nicknames. Is anyone familiar with a way that you can export the Yahoo Nicknames list to e.g. a CSV or similar export file?