In September 2004, Mann founded and began the exclusive writing for the "43 Folders", a blog about "finding the time and attention to do your best creative work." The blog was last updated October 2011. Mann coined and popularized the concept of "Inbox Zero", writing a series of articles in 2006 on 43 Folders, originally suggesting for an "Inbox DMZ". Inbox Zero became associated with the "Getting Things Done" productivity strategy, and is a popular topic on lifehacker. In 2020 Mann stated he doesn't keep his inbox empty, and that the term has been misunderstood.