Gina Ttrapani from Lifehacker has written "Separate your email from your to-do's" an in-depth consideration as to how to turn emails that require action into a "To-Do List".

She says in setting up this discussion:

Your boss needs the updated PowerPoint presentation file by Tuesday. Your spouse wants to know how many vacation days you've got left this year. Your co-worker needs your office pool picks. Everyone gets task requests via email all day long, and it's so easy to let these messages slip through the cracks. Whether your inbox is stuffed with two-year-old fwd'd kitten photos from Aunt Edna, or if you empty it every day and diligently file away actionable email to a "TO-DO" folder - it's still not easy to track the messages you've actually got to DO something about using email.

This is a well-written article providing and devising a way to build a to-do list from emails.

What Nathan Hale pointed out in the comments to this article is that the Linux email program "Evolution" has a cool "convert email to task" as a right-click option, thus turning most of Gina's article to nought. So if you use Linux and have the Evolution program working for you you may not need to read this article.