I use my email software as a some sort of todo list vehicle. Instead of marking emails read I leave them bolded – if they need action. I have categorized my emails in several folders (such as blog, business, team etc.) and whenever a new email arrives I either deal with it and mark it read, or I leave it to check later (and leave it bold). This way I can see with little effort what sort of tasks (business, blog etc.) I have to do.
The problem of this system is that I cannot assign a date for these emails, so I need to have another bigger todo list where I put all the todos that needs to be done on certain date. But other than this, I find the system very nice and easy to use. Much of the communication is done via email, so it’s very time saving way to handle different issues.