https://www.theguardian.com/technology/askjack/2016/jun/02/microsoft-killing-windows-live-mail-what-should-i-do-hotmail-msn-outlook [theguardian.com]

Microsoft is killing off Windows Live Mail – what should I do?

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.

Not sure if anyone here would use this program still, but I'd probably point people to Thunderbird as a good alternative. The article has a few other suggestions as well.

You have until June 30, 2016 to make the move.