The Microsoft Essentials pack, consisting of Photo Gallery, Movie Maker, Live Writer (which is now available as an open source project) and Live Mail, has been in a state of limbo for quite a while now. The latest major update for the pack dates back to 2012 and still uses the Live branding that Microsoft abandoned in the same year.
All of these apps are still available for download, but one of these apps, Live Mail, will soon stop working without the installation of a new required update.
Because of underlying updates on the Microsoft mail platforms (Outlook/Hotmail), Live Mail will lose the ability to receive emails. However, since the application still has quite a few users, Microsoft has provided an update that will prolong the life of the mail application and allow it to receive mails once again.
Microsoft does recommend that any users of the Live Mail application switch over to the new Mail application that has been built-in to Windows 8 and Windows 10. These applications are still actively being developed, so it might be a smart choice to move over, since the support for Live Mail will probably end soon.
This free update is now available here and is dubbed "Update for Windows Live Essentials Mail 2012" (KB 3093594).
Source: Windows Central | Thanks to Faikee for the tip!