My email made me miserable. So I decided to build my own email app from scratch

This is a pretty impressive achievement for a casual programmer. I really didn't expect a working product at the end of it. I enjoyed the article, too.

By focusing just on his own needs, the author created a nice, lightweight implementation of an organizational feature I've seen hinted at in heavyweight clients like Outlook. I can easily see how a team of professional programmers trying to create this for a market would fail, where one motivated amateur* got the job done.

I'd use a thick client version of this, with his keyboard shortcuts, Project view, and easily accessible attachments.

*in its non-pejorative sense.