In early February, Mailbox hit the App Store and impressed millions with its refreshing take on email visualization and triage. An epic waitlist added fuel to the fire, since most people had to wait weeks to gain access to the cloud-powered email app. Mailbox’s impact was so forceful that Dropbox didn’t even wait a month to sweep in and acquire the company within weeks of its launch.

Today, just over three months later, the company is releasing an iPad version of its app, but the Mailbox furor has all but died out. The email app bubble is still bubbling, evidenced by the launch of a several apps like Mail Pilot and Evomail, but these apps face increasing competition from Google itself, which powers the actual email service most of these apps rely on. After years of relative stagnation on the web and no mobile app, Gmail has been picking up the pace and rapidly adding features like the ability to send money to a friend and RSVP to events. It has also been stepping up its game in the design department, a stronghold for apps like Mailbox. Meanwhile, in the "Productivity" category of the App Store, Gmail for iOS is the number one ranked free app, while Mailbox is ranked number 53. Instead of breaking into a wholly untapped market on Android where its focus on design and speed would be well-received, Mailbox chose to build an iPad app. Is it enough to keep the ball rolling?

Mailbox CEO Gentry Underwood declined to talk about how many people are using the app. "I think about it like a stock price," he says. "As soon as you’re publicly traded, everyone’s making short-term decisions based on short-term gains. I want to be smart about making long-term decisions." The company’s first goal was to address one of the top requests from current Mailbox users: a companion iPad app. Mailbox for iPad is little more than a blown-up version of the iPhone app, ported feature-for-feature, button-for-button to the big screen. All the swipes you’ve come to know are here, as is the ability to snooze items for later, browse labels, and quickly reply to emails. The app sends and receives emails in a pinch, as you would expect. The only real difference from the mobile app is that the list of emails is on the left, and the content of emails is on the right, like in the iPad’s default Mail app. There are no signs yet of Dropbox's influence on the app.

Mailbox’s new parent company thus far hasn’t pressured Underwood to integrate its storage features, or even to address the various platforms it has a presence on like PC, Mac, and Android. In fact, it’s been quite the contrary. When the Mailbox team first arrived at Dropbox headquarters in the SoMA neighborhood of San Francisco, it quickly became inundated with ideas from Dropboxers about how to integrate the two apps. "We put all the ideas on a big foam-core board and set up a meeting with Drew [Houston] and Arash [Ferdowsi]," says Underwood. "We asked about what was most important, and what we should prioritize. Drew looked at me with a surprised look and said, ‘What are you asking us for? What’s best for Mailbox users?’"

Down the line, Underwood does see places where Dropbox and Mailbox could integrate, like for attaching files to emails. Dropbox, in fact, already has an API in place that lets iOS developers embed Dropbox file-pickers inside their apps. But for now, Underwood is more concerned with adding functionality to Mailbox. One feature that’s in consideration would let users "snooze" emails not just to specific dates and times, but to specific devices. For example, you could snooze an email to your iPad, since that’s where you check email for an hour before bed.

As Mailbox adds new features, so will Gmail. Mute, one mail triage feature that many Gmail users hold dear, is still not a part of Mailbox. A worrisome scenario emerges where Mailbox falls behind as Gmail adds proprietary features only its users can take advantage of. Fortunately for Mailbox, new Gmail features don’t affect the open IMAP email standard both apps run on, whereas new Twitter features do affect an app like Tweetbot. "Getting locked out? It’s not something we worry much about," Underwood says. "It’s about how we can create the best experience possible around managing mail — by using our agility to do it better than anybody else." Underwood admits that competing with Gmail apps is tough without a desktop app. He and his team are still toying with ideas for how Mailbox on desktops should work, ranging from a Gmail extension (a la Boomerang) to a full-fledged desktop app for Mac and PC. "The jury’s still out, but we need to do it," he says. And yes, he says, Mailbox for Android is in the works.

For those looking for the absolute fastest email experience on iPhone and iPad, Mailbox is still the best option, but it faces an uphill battle against the increasingly design-conscious Google. Powered by Dropbox, Mailbox may move forward unencumbered by server outages, but Google appears more motivated than ever to take its consumer experiences like email and messaging to the next level. Until Mailbox adds additional services like iCloud, Yahoo, and Exchange, it should be playing close attention.

Update: The latest version of Mailbox is now available in the iTunes App Store.