In the Gmail app I have several mail accounts. Today this problem started to occur (it worked fine for months before).
In one mail account the sent messages got stuck. They are in the Outbox folder marked as "Queued". Every now and they they change to "Sending" and then back to "Queued". The other accounts (different servers) work fine. The server type is IMAP+SMTP. The outgoing server settings are identical to settings used on a laptop (Thunderbird app) where they work fine. The laptop and phone are in the same WLAN.
Is there some hidden log or anything that would give a hint? There are no error messages reported at all.