Yahoo is discontinuing older versions of its email client — including Mail Classic — starting this week, the company announced.
"Beginning the week of June 3, 2013, older versions of Yahoo! Mail (including Yahoo! Mail Classic) will no longer be available," it said in a Yahoo! Help post.
After Monday, users can only access their Yahoo email accounts if they upgrade to the new version. The company said users should have received an email informing them of the mandatory upgrade.
Those who want to opt out of contextual ads can do so by changing their settings on Yahoo's Ad Interest Manager.
Yahoo lays out two options for users who don't want to use the latest version of its email client: downloading Yahoo Mail using IMAP or simply closing their account.
Last December, Yahoo Mail underwent a major redesign, unveiling changes to its web, iOS, Android and Windows 8 apps. Its web-based version includes fewer buttons crowding the screen, search improvements, as well as more space to view and compose emails.
"We've redesigned the new version of Yahoo Mail with speed in mind — getting through your emails is faster than ever before," CEO Marissa Mayer said in a blog post at the time.
Do you plan to switch to the new Yahoo Mail? Tell us in the comments, below.