Office 365, Email, Exchange, How to access your account via the Outlook on the Web client
How do I access my Exchange account through a web browser?
You can log in to your Exchange account at: https://outlook.office365.com. On the Outlook Sign in page use your entire University email address NetID@illinois.edu. This will open an Illinois branded login page where you enter your entire University email address NetID@illinois.edu and NetID password. Then click the Sign in button. If you've protected your account with DUO, then you'll be prompted to authorize the access.