Open your Web Browser, then type your URL:- https://sso.godaddy.com/?realm=pass&app=o365
Enter your email address and password of office 365 account.
Enter the button of sign in.
Read more here:- https://assistsuite.com/godaddy-webmail-login/
See Also this post:- http://assistsuite.populr.me/how-to-secure-godaddy-email-login-and-webmail-login