Cornell recently turned on two-factor authentication for all student accounts:
https://it.cornell.edu/news/two-step-login-authentication-will-be-added-office-365-login-students-monday/20200716
A side-effect of this is that now external SMTP and IMAP clients (like GMail) no longer work to send from @cs.cornell.edu and @infosci.cornell.edu email aliases
- Currently there are a few work-arounds:
- Use Mail client like Outlook, or Apple Mail…others listed at link above.
- Use Outlook Web Access: http://outlook.cornell.edu
- Use Thunderbird (version 77+) to configure IMAP account with following settings: