Ironically, Microsoft wanted a web based Outlook, and thats what essentially gave birth to XMLHttpRequest, which was a huge factor in web apps becoming a thing, and launching the web 2.0 era that saw IE get unseated by competition.
Page updates without reloading (AJAX) were a pretty novel thing at the time. Threaded conversations too. And 1 GB of storage! Not 10 MB like others! For free! This was back during peak "Google is actually amazing" era too.
