Back in January, Microsoft launched Outlook for iOS and Android, designed to help users of the two most popular mobile platforms manage their email and calendars. The new apps, which came about after the acquisition of Accompli, is part of the company’s push to provide productivity tools across platforms—even those it doesn’t own. In the case of Outlook, that seems to be paying off.

Microsoft announced Wednesday that 30 million people use Outlook for iOS and Android every month. That’s some serious traction for a heavy-duty productivity app, and it also consistently holds a position among the top 20 most downloaded productivity apps in both the Google Play Store and iOS App Store. (In the grand scheme of things, Outlook’s position isn’t nearly as strong as Facebook’s, which reported in July that it had one of the most popular apps with 1.31 billion monthly active users on mobile.)

Now, the two apps are getting a visual design refresh, thanks to some help the Outlook team got from the people behind Sunrise, which Microsoft acquired and added to the Outlook organization. Long-time users of Outlook on either platform will notice the subtle differences between the past version of the app and the new design, but it’s not a radical shift.

On iOS, the inbox layout now shows new, colorful icons that denote event invitations, and the attachment and flag icons are more prominently displayed on the right hand side of a message in the list in keeping with the app’s counterpart on Windows. Thanks to the Sunrise collaboration, the calendar is also getting a facelift with fit-and- finish changes like showing the day’s date in its icon, and better displaying multiple calendar events at the same time.

Android users will find that the app fits better with the overall system design and material design principles that are common across Android apps. There are some other tweaks coming too, like an inbox that shows images of the contact who sent an email if a user’s address book has a picture for that person. While the iOS update is available today, the Android update won’t be rolling out for another couple of weeks.

Sunrise Calendar fans should also be aware that the team’s contributions to Outlook will soon be more than just working on the design of the Outlook app itself. Javier Soltero, the corporate vice president of Microsoft Outlook, said in a blog post that the end goal is to bring the features of Sunrise into Outlook, and eventually replace the current Sunrise app with Outlook entirely.

Soltero is something of an outsider to the Redmond, Washington-based tech giant. He joined when Microsoft acquired Acompli, the company he co-founded. Now, he’s charged with building out Microsoft’s entire suite of email clients, from the popular Windows desktop app to the email client on iOS and Android. Under his leadership, the Outlook team has changed focus toward building apps that share the same principles, but don’t necessarily look the same.

“Before I got here, the charter for the Outlook team was about consistency, and they believed that things needed to look the same, and what made Outlook, Outlook was a visual thing,” Soltero said in an interview. “And it’s not. Because if you do that, then you’re presuming that I want to see an app inside of [an iPhone] that was really made for [Windows Phone].”

Instead, Soltero said that he’s focused on pushing a coherent vision across platforms for what Outlook does, even if its applications aren’t a pixel-by-pixel match for one another. To that end, people should get ready to see some of the features from Outlook for iOS and Android, like a “Focused” inbox that shows users’ most important emails, on other platforms where it hasn’t appeared before.

In Soltero’s view, it’s important for the Outlook team to keep pushing forward and rapidly adapting its product to users’ needs, especially given the competetion for users in the mobile applications space.

“So, we have to be able to evolve the product with a higher cadence, and with an eye towards what is going to make that product first and foremost be chosen by people,” Soltero said. “And particularly because the phone ships with another email client. So the discussion for Outlook starts with ‘How is it better than what comes with my iPhone or my Android device?’”

Looking forward, Soltero wants people who are using Outlook to be able to sync their settings across devices, so tweaking a preference in one app will propagate across each application someone is using. All of these changes could prove to be a long-term benefit for Microsoft overall: If people are thrilled by using Outlook on their phones, they may be more likely to pay for it on their PCs or Macs through an Office 365 subscription.