@Tuta
I notice a difference in my mails shown to me in the Linux desktop app and the Android app. The former shows only one mail, the latter shows all mails that checking via a browser shows. I've checked that the filter is set to 'all emails' for all.

It seems related to the 'local data' setting which for both apps is on the default of one month and all missing mails are older than one month. So I've changed this to 366 days for both clients.

However, the old mails still do not show up in the desktop app. Is there another filter I'm missing?

How can I use the desktop client to see all mails I can see via the browser?