The email cannot be sent if either of these is missing, and therefore it’s a necessary complexity. To reduce this complexity, a modern email client will do two things: prepopulate the sender (it can do this because it is aware of your email address), and provide suggestions for the recipient as you begin to type their address, based on prior emails and/or your contacts (Figure 9-1). The complexity isn’t entirely gone; it’s just abstracted away to reduce the effort required of the user. In other words, the experience of writing an email is made a little simpler by moving the complexity of filling in the sender’s and, if possible, the recipient’s address to the email client, which was designed and developed by a team that assumed that burden of complexity when building it.