Ubuntu 19.04 / MATE
I have two gmail accounts which I can access for IMAP in Mailspring and Thunderbird.
Sylpheed gives no error through the UI. The sylpheed log has only a debug statement.
DEBUG: Name com.canonical.AppMenu.Registrar does not exist on the session bus
Clicking Get, Get All has no effect on either account. Get All checks for new mail is enabled on both accounts.
General setting : Get new mail on startup is enabled. Sylpheed has been restarted.
Both accounts have way way way too much unread mail, but sylpheed is not pulling any of it down.