Office365: DUO Troubleshooting for Web-based Email
"Access Denied. The username you have entered cannot authenticate with Duo Security. Please contact your system administrator."
Due to your UT EID's affiliation, your account is not eligible for DUO and cannot use second factor authentication. This can happen with a guest class EID that has a mailbox associated with it. We suggest that the mailbox owner create a resource mailbox for shared mailbox use. The ITS mail team is prepared to assist TSCs with converting guest EID mailboxes to shared or resource mailboxes (or distribution groups). Contact us at firstname.lastname@example.org or open a ticket with the UT Service Desk. More information can be found at KB0017092.
If you have any questions or need assistance managing your DUO account, please contact the UT Service Desk at 512-475-9400 or email@example.com.