When using Kmail with multiple accounts and a lot of folders, Kmail tends to forget the correct mapping of Sent and Draft folders sometimes.
STEPS TO REPRODUCE
1. Set up several identities and configure several Sent and Draft folders.
2. Use (and update) KMail a long time.
Sometimes the configuration is mixed up and the Sent and Draft folders point to random other folders.
The configured mapping remains the same.
Linux/KDE Plasma: Gentoo, KDE Plasma 5.21.4
(available in About System)
KDE Plasma Version: 5.21.4
KDE Frameworks Version: 5.81.0
Qt Version: 5.15.2
I'm pretty sure, this bug is known, but I didn't find it in the tracker. I have experienced this a long time (several years), always occasionally.
I could also kind of reproduce it, when I delete the Akonadi database (I have deleted the entire folder ~/.local/share/akonadi). In this case, Akonadi syncs again (all settings are preserved) but the mapping is gone or mixed up.
Since quite a time, KMail also displays a message, if the folders cannot be assigned anymore.
Therefore, I would guess that the mapping is not string based but indices based and the indices are assigned randomly, when Akonadi creates a new database.
However, this does not only happen when deleting the database. In rare cases, it also happens without any obvious reason (maybe an update?).
This whole reassigning could be quite dangerous with sensitive data. Let's assume you have two E-Mail accounts: "A1" and "A2" (both IMAP, both have an INBOX and a Sent and Draft folder). KMail is configured to put sent messages of A1 to the A1.Sent folder and drafts of A1 to the A1.Draft folder and the same with A2.
Now the mixup happens and A1.Sent points to A2.INBOX. After that, you send a message from account A1. KMail sends the message, puts it additionally in A2.INBOX, marks it as unread there, uploads it to the server (it is IMAP!) of the A2 account, the server executes some Sieve filtering and since A2 is a shared account, the mail is sent to a bunch of people. (This happened to me today. It was not a sensitive content, so the is was not that bad, but nevertheless unpleasant.)
Is it possible to change the assignment/mapping to a string based approach?