In May 2015, Microsoft announced a major update to its consumer-focused Outlook.com service, which would include changes to its front-end user experience and back-end infrastructure. Today, Microsoft literally has no idea when it will ever complete this migration.
It's become a running joke, of sorts, assuming you're a fan of gallows humor. According to my calculations, it's been 467 days since Microsoft announced it was starting the Outlook.com migration. And Istill don't have it.