Gmail on SeaMonkeyYes, you can still connect it after the switch to OAuth2. You need to create a placeholder account first, and find the right settings, which Gmail doesn’t seem to tell you anymore.
How Thunderbird’s Scam Detection Works (2005) (Obsolete)
Tracking down what causes Mozilla Thunderbird to label a message as suspicious, as well as how to train it to ignore emails that you know are legit.
Move Email Archives to a New AccountThunderbird, Vivaldi, Apple Mail and Outlook can move messages from one IMAP account to another. Just drag and drop! But Gmail makes it a bit more complicated.