I'm an Exchange user. Why can't I log in to webmail.mit.edu?
When an Exchange user logs in to the legacy Webmail system, they will be redirected to the login page, and they will get a message that says
Your email account is provided by MIT's Exchange email service. Please access your MIT email by visiting http://owa.mit.edu.
Note that this message is displayed above the username box, so it might not immediately stand out on the page.
The message looks like this: