When I delete an email I want it gone, immediately. Not copied to Trash from where I need to cleanup later. Likewise when I send email I do not want a copy stored in a Sent folder, I’ll CC myself on the rare occasions when I need to keep a copy.
This works fine with other mail clients like Thunderbird on Windows and Linux, but in K9 on Android (version 18) I have gone to the Settings->Account->Folders, and set Sent folder to “None” and Deleted Items folder to “None”. This works for a short while (an hour or so), but then K9 resets these to “Automatic(Sent)” and “Automatic(Trash)” and I suddenly find these folders created and cluttered up with unwanted messages, which is absolutely infuriating. How do I stop K9 from resetting these values?
There’s a TBA bug report open on github discussing the trash folder assignment reverting after being set to none. You should consider adding your findings to that ticket, linked below.
This behavior often happens when the app performs a folder list refresh with the IMAP server. It seems like the server-side folder discovery might be overriding your local preferences during the sync process. You could try checking if your email provider has specific ‘special folder’ flags enabled on the server side that are forcing these back into the app.
I would only expect the app to take a value from the server if the app settings are “Automatic”. If the app has a specific hard-coded value in place (even “None”) then I would expect it to honour that. It seems from the other thread that this is a problem with Thunderbird, which K9 is now based on, others have reported the same issue with Thunderbird.