Outlook.com customers use the Reply button almost 8 million times a day which are 50% of the usage of compose. With inline compose, you can directly respond to an email thread without launching a new view. Inline compose can help you save time, and track your conversations more easily.
I was the lead designer on this project and worked with PM, researcher and developers. The goal of this project is to create a composition experience that responds well to conversational forms of email threads, as well as reduce full screen transitions to improve the perception of fluidity of workflow in the product.
Inline compose gives user fast and fluid experience to quickly reply in the conversation.
When you need more concentration, the full compose is one click away.