According to the Yahoo! Mail app page maintained on the Microsoft website, Yahoo! Mail is available in Spanish. As of May 2014, Yahoo Mail! is also available in 31 other languages.
Other languages available for Yahoo! Mail include English, German, Italian, Japanese, French and Chinese. To change the language displayed, the user must navigate to the Edit My Account page and then to Yahoo Account Info on the main Yahoo! site and click "Edit." Once at the Edit page, the user can select the desired language and country settings from the drop-down content menu, and then click "Finished" to save the results.