Having only an outbox displayed occurs when the account's sign-in didn't complete successfully during setup or import. This can happen if the Oauth 2.0 account sign-in process was skipped or an unsupported configuration was imported. Is the account using ... # Imap or pop3 connections? # What authentication type is used on each. Oauth 2.0 or user name & password. For the two accounts, can you navigate to # Settings > account > fetching mail > incoming server. # Settings > account > Sending mail > outgoing server. Click next on both screens to establish and test the server connection. Port 993 = Imap, Port 995 = Pop3 on the incoming server page. For oAuth authentication, you might be prompted to sign-in to your provider and grant the app permission to access your email account. Click the "sign-in with google" button as example. Note that Thunderbird for Android doesn't support using OAuth with Pop3 connections. If this is the issue, you will need to create an app password via your webmail setting.