Collin Fletcher of The Tech Block makes the solid case that the acquisition of iOS email app Mailbox by Dropbox signals the latter company’s push to build a “windowed ecosystem” on top of its core file syncing service. It’s worth reading the whole article, but I’d go a step further.

Victoria Barret of Forbes reported in October 2011 that, as Dropbox CEO Drew Houston told her in an interview, Steve Jobs called the company a “feature, not a product” when Houston rebuffed Jobs’ acquisition offer.

Steve was wrong, though. Dropbox isn’t a just product (although plenty of people pay for its core sync functionality), nor is it merely a feature (although it can be integrated into many different types of apps and services).

Dropbox is, at its most fundamental level, an infrastructure. What the Mailbox acquisition really signals is that Dropbox is confident enough in its core service that it is time to invest in ways to add value to that service. The Dropbox file storage and syncing infrastructure already undergirds the daily workflows of millions of people.

Email is the perfect product to build on that infrastructure. So is a personal music storage and player product. So is a task manager. So are innumerable other products that benefit from a powerful, reliable file synchronization mechanism that can functions flawlessly at scale.

If you’re composing an email you don’t want someone to see, consider picking up the phone instead. Your assumptions about the privacy of email are inaccurate.

Abdel Ibrahim, interviewing Mailbox founder Gentry Underwood at The Tech Block:

Any plans for an Android app?

Definitely. Startups focus or die, so we picked one device (iPhone) and one platform (Gmail) to start, but we’ve designed our infrastructure from the beginning to support scaling to other devices and platforms as quickly and easily as possible once we feel Mailbox is “working” on the first set.

Good news, because it’s beautifully-designed and functionality looks to be top of mind from the screenshots I’ve seen.

Austin Carr, writing at Fast Company's Co.Design blog:

It’s actually proved to be a more modern and nimble alternative to many of its mainstream counterparts, and boasts many novel features that Google, Yahoo, and Microsoft, even with its beautiful redesign of Outlook, should all heed lessons from.

His review has some images and a really good explanation of how Alto feels. Fast Company's Adam Bluestein spoke with Alto's team leads, and that article is also worth a look.

The articles compare Alto to Pinterest, but it looks to me more like Evernote, with note titles and summaries on the left and notebooks in a larger “stack” layout pane on the right. Regardless, it looks elegant and functional, which is what I want from websites and apps. I’m really impressed by how it looks and the philosophy behind what they did, including empowering an insular team to build it outside of Aol’s larger structure.

In fact, Alto looks so well-designed that, if I was in charge at Aol, I probably would have had them launch without much of a mention of Aol at all. It’s unfortunate but true that the Aol brand is really a handicap to anyone trying to do something as bold as redesigning how we use email. Some people may see “Alto, by Aol” and skip it altogether. I almost did.

Alto works with many popular email services, including Gmail, so I’m excited to see how it works. You can request an invite here. I’ll write something more in-depth when I get the chance to try it out.