Thunderbird is no longer working after the implementation of two-step for UCSD emails.
Thunderbird email client will need to be v.78.0 or higher in order to use multifactor authentication. Older clients will not be able to use Duo Two-step and will no longer be compatible with UCSD email.
If you still have questions or need additional assistance, please submit a ticket or call the ITS Service Desk at (858) 246-4357