Microsoft has released another new Windows 10 “Redstone 5” test build that includes a new controversial change meant to get more people to use Microsoft’s Edge browser.

Windows 10 test build 17623, which Microsoft released on March 16 to testers in the “Skip Ahead” ring, is the first to test a change “where links clicked on within the Windows Mail app will open in Microsoft Edge” regardless of the browser that a user has set as default.

Even though it continues to bundle its Edge browser with Windows 10, Microsoft has made no headway in blunting Google Chrome’s dominant browser share on Windows 10 PCs. Because the browser is one of the most, if not the most, frequently used applications on Windows, Microsoft continues to try to find ways to get Windows users to try it. But Microsoft’s campaigns around security, battery-life improvements, and integration with other Microsoft apps have not convinced the majority of Windows 10 users to go with Edge.

Build 17623 also includes the Windows Defender Application Guard and System Guard improvements which Microsoft introduced earlier this week in its latest Windows 10 Redstone 4 test build for Fast Ring testers. It also includes the privacy-setup changes around Inking & Typing and Find My Device that Microsoft added recently to Redstone 4.

Additionally, today’s Skip Ahead build adds support for High Efficiency Image File Format (HEIF) in the OS and Photos app. According to Microsoft’s blog post, HEIF is an image container leveraging modern codecs to improve image quality and compression. To test this feature, Insiders also need to be part of the Windows App Preview program for the Photos app.

Build 17623 includes a fix to the Microsoft Store being broken or missing issue, as well as fixes to some of the Mixed Reality problems in recent test builds, among other changes and improvements. Microsoft also has updated the Cortana section in its Settings in this build so it’s now called “Cortana & Search.”

Today’s blog posts also lists several known issuesthat testers should check out before installing this build.Redstone 5 is due out this coming Fall, likely around October.

Microsoft also released Build 17123 to the Fast Ring for Windows 10 Redstone 4 testers today. This build adds the aforementioned HEIF support, plus fixes a number of the Mixed Reality issues that were in the Fast Ring test build released earlier this week.