I am only coding in Objective-C and I have no experience with backend coding, only a high-level understanding.

I understand why a lot of programming projects require backend servers but I'm not absolutely clear on a high-level perspective why Mailbox needs their own.

They get their data from the Gmail API,

It is my understanding that most iOS client app receive data from a backend from a public API (like Gmail), download in the iOS app and show it in their app. Therefore they have no need for their own servers in order to receive the appropriate data to show it to their users.

My only explanation is that Mailbox follows this logic:

Gmail data --> Mailbox's app AND servers --> users interact with app --> save changes on their own servers and Google's via the API

The last part to me would mean that they would basically keep the data of all the Archived, Delayed, Deleted, and Listed emails on their own servers rather than Google's.

Is my understanding correct?

Thank you

2 Answers 2


One good reason to build things with an intermediary service you control is so that you can control your own destiny and control when you need to change the app. For example, if your mobile app was talking directly to google and then they change the API surface you would have to push out an emergency update. This would be doubly bad if the change broke key features of your app. Another case is if google cut off your API access -- at least your app would have whatever you stored in your cloud. There are many other use cases but if I were building something like this I would certainly strongly entertian the idea of at least building my own proxy service.

  • This is very informative, thank you. It makes a lot of sense from a technical perspective. Commented Mar 25, 2014 at 22:05
  • Except GMail uses IMAP, which isn't going to change any time soon. Commented Aug 30, 2015 at 14:10
  • @GrahamChristensen -- my understanding is gmail exposes IMAP for other consumers but their own apps use different interfaces. Commented Aug 31, 2015 at 22:01

Your suspicion is about right. There really should be nothing that the client couldn't be able to take care on its own unless the server also offered to save information that otherwise could not be saved using Gmail. It could be that, in fact, this is the reason and that Mailbox requires to store additional information.

However, I'm more inclined to think that the true reason is the same reason why the application is free. In this way, they offer you the services of their app in exchange for free information. This is not that unusual, but I think often people tend to forget that free apps get their money elsewhere.

Make no mistake, Google does this too, however they tend to use it to know what types of advertisements you'd click on. Mailbox may use it for this purpose as well, but more likely the information is sold to the highest bidder. My advice is to interface directly with Gmail if it is possible.

  • 1
    Good point. When you use apps that are offered for free, your are the product.
    – Bart
    Commented Mar 25, 2014 at 18:37
  • Great answer. I didn't know that Mailbox or other clients could sell information such as gmail/facebook etc. since I thought that Google owned that information. Commented Mar 25, 2014 at 22:03

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