I've used Thunderbird with multiple Google Workspace accounts before - but I've found the account configuration process to be very inconsistent. All three accounts require OAuth2 authentication - all use the same IMAP and SMTP servers. Adding the first account works perfectly - every time. It's when I go to add the second account that I start encountering issues. I'll see one of two things happen: 1. A browser window will instantiate but it will attempt to use the login from the first account to authenticate the mailbox for the second account. Obviously that's not going to work, so I cancelled out of the authentication workflow. 2. Now that I've cancelled the authentication workflow, Thunderbird attempts to use basic auth each and every time. I've deleted the account and tried adding it back again. No luck. I've had this working on a couple of other Windows computers. But, as mentioned at the onset, the behavior was very inconsistent. Now, I'm setting up a new computer and I'm stuck. From what I've seen in other email clients - they seem to understand that each mailbox will require unique credentials. They do not attempt to reuse OAuth2 tokens for subsequent mailboxes. Instead, they restart the authentication workflow for each account - which is the behavior I would expect with Thunderbird as well. This seems like a bug. I'm not sure how to troubleshoot it any further. This is with version 128.3.2esr on Windows 11 (24H2).