First reason why I started to use K9 mail was that original android e-mail client was not able to synchronise all folders (subfolders in one account) by one tap at one button.
I want to sync all by one action when I am at WiFi, and to keep disposal messages in local storage (cache) when I am out of WiFi.
Original K9 mail had button for sync not only at subfolders, but also at account view (folder list)
and at accounts list (to sync all accounts).
I can not find this option any more.
I would like to have possibility to sync current folder or to sync whole account.
Eventually to sync current folder as first, and rest of account(s) then.
I do not know how to do it in this new demoversion of e-mail client, which does not have anything from real K9 mail.
(The whole issue is not wifi/nonwifi topic only;
it is also difference if I see info about new messages for concrete folders when I am in folder list, or not see.)