How to Export Your Yahoo Mail Address Book
If you change email providers, take your list of contacts with you. Use Yahoo Mail to export your address book to a universal format: CSV. While importing email addresses from CSV files may not always work perfectly with all email providers, most major services, such as Gmail, support the format flawlessly.
To export your Yahoo Mail address book to a CSV file:
Select the Contacts icon in the upper-right corner of Yahoo Mail. It is located to the left of the Settings, Calendar, and Notepad icons. Select the check box above the contacts list to select all contacts. You can also select or deselect contacts individually. Select the Actions drop-down menu. Select Export. Select Yahoo CSV for a generic . csv file. There are also options for specific email providers, but the CSV format is the most universal. Select Export Now to begin the download.
Yahoo Mail saves the contacts to the default download folder in a file named yahoo_contacts.csv. Import the CSV file to Outlook or any other email service.