Having only one inbox can make it easier to keep track of your messages
The more inboxes you have, the harder it is to keep track of your messages. Messages accumulate and get buried in the different inboxes. When someone sends a message to a contact in one of your other inboxes, you might never know that they got it. It’s annoying having old messages sitting in your mailbox. Deciding what to do with old messages is a decision that you make once you’ve read them (which takes time). The goal of this study was to see how an individual would respond to having more than one inbox.
The subjects were presented with one of three scenarios: they had several inboxes, they had two inboxes, or they had one inbox. The particulars of the scenario were identical in all three cases; the only difference was in how many inboxes the subject had. To decide which scenario to use as a baseline and which scenario to use as an experimental condition, I used a process called simulation. A simulation is a method that allows you to create pairs of things that aren’t identical. In this case, if one inbox is created, the other inbox may be different than the control.
For example, in the baseline and control scenarios the subjects were presented with three subject-number pairs. In the baseline scenario (multiple inboxes), the first subject-number pair was offered a new iPhone and asked to choose among three options: sell iPhone, keep iPhone and cancel iPhone order. The second subject-number pair was offered a new iPhone and asked to choose among three other options: sell iPhone, keep iPhone and cancel iPhone order. The third subject-number pair was offered a new iPad and asked to choose among three other options: sell iPad, keep iPad and cancel iPad order.

You can easily see which emails are important and need a response
The more inboxes you have, the harder it is to distinguish which emails you need to respond to. If you have hundreds of emails in your inbox and can’t tell which ones are important, do what most of us do––archived everything. It’s annoying having old messages sitting in your mailbox. Deciding what to do with old messages is a decision that you make once you’ve read them (which takes time). If you archive everything, the time you spend deciding what to do with old messages will be spent only once a year. (If you have dozens of messages that are still waiting for a response, why are they still there?)
Also, you can’t archive everything. If you were to archive every single email, your inbox would be 99% archived mail. The only way to get a sense of what you’ve archived is by going to the All Mail folder. Those messages will sit in your All Mail folder until you decide to move them back into your Inbox. If you have hundreds of old emails sitting in your All Mail folder, you’ve already decided to ignore them. What’s the point in having email if you can’t keep track of it?
