Trying to iframe https://login.microsoftonline.com/ on a VF page.
However, I get the error: Refused to display 'https://login.microsoftonline.com/' in a frame because it set 'X-Frame-Options' to 'deny'.
Is there anything I can do?
DENY: The page cannot be displayed in a frame, regardless of the site attempting to do so.
You could instead open the URL in a new window rather than embedding it in an iframe.
Simple answer: There is no solution for this, the X-Frame-options is set to deny at the header level.
Microsoft may be doing this for security reasons, have a button to redirect your users to the login page of microsoft instead of iframing the login page.