Windows Live Mail is a desktop email program Microsoft introduced to replace Outlook Express. It is part of the Windows Essential suite, which includes several programs: Live Mail, Live Writer, Photo Gallery, MovieMaker and OneDrive. (It used to include Messenger, which was replaced by Skype.) The suite has not been updated since 2012, because Microsoft switched to developing securely sandboxed, touch-oriented apps instead.
Windows Live Mail 2012 will not stop working, and you can still use it to download emails from any standard email service. However, Microsoft is moving all its own email services – Office 365, Hotmail, Live Mail, MSN Mail, Outlook.com etc – to a single codebase at Outlook.com. Windows Live Mail 2012 does not support the new APIs (applications programming interfaces) required to provide full synchronisation with Outlook.com. Microsoft could update Windows Live Mail 2012, but instead, it has asked users to switch to a different email program.
Microsoft suggests using either its free Mail app or Outlook, the email and personal information manager that is part of Microsoft Office. Outlook costs money, but Microsoft is offering Live Mail users a free subscription to Office 365 for one year. (You should have received this offer by email, but if not, the details are online).
The Mail app only runs on Windows 8/8.1/10, but not on Windows XP/Vista/7. Some people who want to use the Mail app will have to upgrade to Windows 10 to get it.