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Beware of Email Apps Storing Passwords

Email apps, especially ones that offer advanced services like “send later,” may be storing our usernames and passwords on their servers.

To be clear what that means: if you use Gmail, for example, you put your Google username and password into the app when you set it up. You expect the app to store them securely on your device. But some apps may also be storing that username and password — your keys to all the Google services in this example — on computers owned by the company that makes the app. Computers over which neither you nor Google has any control.

I’m not suggesting that the company I talk about below, or any other, is doing anything nefarious. They need to be able to log in to your mail server in order to send your mail later. But I hadn’t realised until now what that means, and I’m guessing neither will a lot of people. And to my mind they don’t make what they’re doing clear enough.

Worst of all, having passwords stored on unknown servers — at the very least, that’s worrying.

Background

On episode194 of the Connected podcast, Myke Hurley and Federico Viticci were reviewing the latest version of the iOS (and Mac) app Spark. It’s a fine email app, which I was using on my iPhone and iPad. So I was alarmed when they mentioned in passing that mail handled by the app is routed through Readdle’s servers. That didn’t seem likely at first. Spark is an email client. You tell it what servers handle your mail, and it connects to them to receive and send. The servers belonging to the company that makes the app have no business getting involved in that.

I did some digging. Whether or not Myke was right™ about mail going through their servers, the reality turned out to be much worse.

Digging

I tweeted at the Spark account. Here’s what happened:

I had already found their privacy policy:

OAuth login or mail server credentials: Spark requires your credentials to log into your mail system in order to receive, search, compose and send email messages and other communication. Without such access, our Product won’t be able to provide you with the necessary communication experience. In order for you to take full advantage of additional App and Service features, such as “send later”, “sync between devices” and where allowed by Apple – “push notifications” we use Spark Services. Without using these services, none of the features mentioned above will function.

The wording “Spark requires your credentials to log into your mail system in order to receive, search, compose and send email messages” suggests that Spark the app needs to log into your server, which it does. But nothing about that says that your credentials will be stored on their servers.

Further down, in point 4, “How Long Personal Data is Stored For,” in a table that includes “Type of information,” we see (emphasis mine) :

Email address, email content for Spark Services, mail server credentials

So there it is. They do store your username and password on their servers, and they do tell you; though only if you read well into the kind of document that notoriously goes unread.

Final Thoughts

For features like “send later” they need to store the fact that you want to send an email at a specific time, and log in to your server in order to send it. And to be fair, I’m sure they can’t be alone in keeping that kind of data. Lots of clients offer “send later” and similar services, and all of them will have to log in to your mail server to work. So they have to store your credentials on their servers to do it.

And consider, if you use Gmail, that means your username and password not just for Gmail, but for all Google’s services, are now stored on somebody else’s servers. Their security might be great, but how do we know?

The more I think about this, the more concerned I become. Passwords should only be stored in one place: a secure, trusted password manager. But above all, these services need to be much clearer about the fact that they’re storing our passwords.

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