Outlook user Adam Wright describes how he automatically filters incoming messages and uses flags to create a to-do list folder alongside his inbox.
Outlook’s “Follow Up” folder (normally two folders below the “Inbox” folder) only shows emails with a follow-up flag assigned to it. By using follow-up flags, I can now use my “Follow Up” folder as my todo list (notice I changed the name of my “Follow Up” folder to “To Do”).
We like to separate our email from our to-do’s around here, but that’s not everyone’s cup of tea. Adam’s method could easily be used in any mail client that supports flags or tags (like Thunderbird), too.