Users will only be able access their Yahoo email accounts if they upgrade to the new version.
The firm has announced that starting today, Yahoo Mail Classic will no longer be available.
Those wishing to opt out of interest- and contextual-based advertising can change their settings using Yahoo’s Ad Interest Manager. Those who don’t want to use the new Yahoo Mail at all are given the option to use IMAP to access emails from a different program, or simply close their account.
Yahoo has been streamlining its services over the past four months. Back in March the firm announced it would discontinue seven products, including its Blackberry app and Yahoo Message Boards.
In April Yahoo confirmed that another six were being axed, including Yahoo Mail for feature phones.