Equip akonadi with the possibility to write emails to disk that akonadi knows about in its database and that are missing at disk. At the moment I've the following amount of emails at disk. But kmail reports for sent-mail 13292 and for trash 307 emails. unread totaal folder 0 53 inbox 0 0 outbox 0 13290 sent-mail 0 302 trash In case of recovery and the akonadi database is to be restored from scratch, not all emails from sent-mail and trash will be restored (as these are not disk, but are only known in the akonadi database). The feature could be added to akonadictl, akonadiconsole or to e.g. kmail. https://phabricator.kde.org/T638 seems to be related.
Indeed we need some kind of mechanism for this, this has been on my todo list since forever. Server-side change recording is definitely going to allow for this, but already with payload notifications we might be able to implement this inside of Monitor (so client-side).