PostHistory visualizes users' email mailboxes and the activity patterns within them. The idea is not to create yet another email reader, but instead is an attempt at making activity patterns within one's email account visible and visually interesting. Some of the questions in the project are: how much email do you get on any given day?; how active are you in replying, deleting, or moving messages around?; and how different does your mailbox activity look from someone else's?