After a bungled blog post leaked the news last week, Microsoft has confirmed that it is acquiring Acompli, a start-up specializing in email apps for mobile platforms. It is believed that Microsoft paid upwards of $200m for the company, saying that the buy was part of its effort to improve mobile productivity. Broader than that, the purchase can be seen as an important part of CEO Satya Nadella’s mission to loosen the company’s ties to Windows and make it a cross-platform software and services powerhouse, especially in the mobile and embedded spaces where its own OS has not gained a dominant position. The Acompli app, unusually for third party offerings, supports Exchange and making the most popular professional email client…