Every time I start Thunderbird, I get this error:
The current operation on 'Trash' did not succeed. The mail server for account email@example.com responded: [NONEXISTENT] Unknown Mailbox: Trash (now in authenticated state) (Failure).
I've figured out that it goes away if I create folders in my Gmail accounts called "[Imap]/Trash" and "[Imap]/Sent", but why are these necessary? Even if I tell Thunderbird to unsubscribe from them, it still notices when I remove the labels and starts popping up this error again.
One account also complains if I remove the "Sent Items" label.