Q. What do I need to do?
https://blogs.office.com/2016/05/05/using-windows-live-mail-2012-with-outlook-com-time-to-update-your-email-application/
A. We recommend that you switch to the Mail app that is built in to Windows 8.1 and Windows 10. You do not need to install any software; simply launch the Mail app, navigate to “Add Account” and enter your Outlook.com email address and password. Because the data in your Outlook.com account is stored in the cloud, there is no need to manually move it from Windows Live Mail 2012 to the Mail app.
(´-`).oO(起動しなくなるメールアプリに移行汁と)
5/13 追記
Windows Live メール 2012 と Outlook.com をご利用になっているお客様へ: メール アプリケーション変更のお願い - Office Blogs