As of August 21, 2020, all alumni and retiree emails will require 2-Step Verification for Gmail. Some accounts may have been locked when MFA was implemented.
Follow the Gmail Two-Factor Authorization setup to gain access to your account.
On rare occasions, if you still have access to TU resources through your TUNetID and not just to Gmail. The MS TUNetID account passwords DO NOT sync with Gmail, so if you changed your password for your TUNetID in May 2020, you will need to use the old password for your Gmail login.