Kmail won't download email

[Erik Quaeghebeur]

> Our law firm has used kmail for many years and supports kde.

Nice!
  
> My secretary's 
> kmail won't work and produces error messages, including:
>
> Unable to store downloaded emails.
> Failed to append item.
>
> She uses Debian buster.  Our IT guy (who is familiar with 
> linux) has spent two days 
> trying to fix it without success.

You (or your IT guy) should provide far more information:
* What has been tried already?
* What type of mail setup (IMAP, Maildir,…)?
* What backing database (SQLite, MySQL, PgSQL)? Is it running?
* Are other Akonadi services also blocked (contacts, agenda)?
* What can be seen in the logs? (journalctl and then search for akonadi 
around the time of the error message)

In any case, what you can already try (after creating a backup):

1. in a console: akonadictl fsck

(if not yet fixed by 1.)
2. delete akonadi database and recreate it


Success,

Erik