Microsoft's brand new Mail and Calendar apps for Windows 10 have been revealed early by a leaked preview build that has surfaced online. They look a lot like Microsoft's new Office apps for Windows 10, and they should be available in an upcoming technical preview.

Microsoft briefly demonstrated the new apps during its Windows 10 press event back in January, but they are yet to appear in any of the Windows 10 preview builds that have been rolled out to testers. However, it seems Microsoft is now close to making them available.

"The Mail and Calendar apps are fairly basic right now, but they're also very functional and incredibly fast and smooth to use," reports Tom Warren of The Verge. "They both feel and look a lot better than their existing counterparts in Windows 8.1."

The Mail app includes new customizable swipe gestures that are baked into Microsoft's new Outlook apps for Android and iOS, support for multiple accounts, and simple setup for services like Outlook and Gmail. While it is called Mail for now, the app is expected to be renamed Outlook ahead of Windows 10's public launch this summer.

The Calendar improvements include support for Google Calendar (finally!), including shared Google calendars. But Microsoft seems to be keeping it separate from the Mail app, whereas email, calendars, and contacts are tied together in the Outlook apps for mobile.

This leaked Windows 10 build, which has version number 10051, also includes a new Microsoft Family app for managing parental controls, and minor changes to other apps, such as an "open in Internet Explorer" option in the new Project Spartan browser.

It's unclear whether this particular build will be made available to Windows 10 testers, but the new apps and changes will certainly appear in a public preview at some point.