I came across similar questions at a few online forums such as MSDN and Stackoverflow and thought I’d share the answers. A direct answer to the question is “No, you cannot”. Since supported APIs in .NET for Windows Store apps do not include email function as the full .NET framework does, you cannot create email directly. An indirect answer is that you shouldn’t have to because you can use the sharing function in Windows 8.
How do you share a file and send the email out? Check out the MSDN sample. It shows how to share text, link, image, files, and error message in case a file cannot be shared.
For Windows Phone 7/8 apps, you can use third-party components such as LiveMailMessage 1.0.3 by Venetasoft.