Re: Kmail won't download email

> I expect, that you are catch bug https://bugs.debian.org/1031770. A security 
> fix of MariaDB changed the way they return their internal version, that break 
> Akonadi.

If that is correct (and the bug report seems to suggest so), then (temporarily) switching to the sqlite backend may be a workaround. I guess you'll need https://packages.debian.org/buster/akonadi-backend-sqlite, delete the current config+database (backup first!), manually configure the sqlite backend, and then do a first run to repopulate the database. I've been using the sqlite backend for years now and it is not worse in my experience than the MySQL/MariaDB one. 

The relevant config file seems to be ~/.config/akonadi/akonadiconnectionrc:

Mine looks like
---
[Debug]
Tracer=null

[%General]
Driver=QSQLITE3

[QSQLITE3]
Name=/home/equaeghe/.local/share/akonadi/akonadi.db
---
I think you can leave out the [QSQLITE3] part when manually configuring it, as it gets created on the first run.


Success,

Erik