Comment 12 for bug 1821868

Possible workarounds:

1) Let Kmail or Kontact crash; close any remaining email config window without doing anything in it; start Kmail or Kontact again. Application should now start ok.

(This is probably what will happen for most people, on purpose or just as a matter of course)

or;

2) Prior to starting Kmail/Kontact, in a terminal run 'akonadictl start'. This initialisation of the akonadi db seems to avoid the race condition later when mail client is started.

or;

3) Prior to starting Kmail/Kontact, create ~/.config/specialmailcollectionsrc with the content:

[SpecialCollections]
DefaultResourceId=akonadi_maildir_resource_0

Note: While this (3) superficiality appears to work, it is not well tested for longer term impact on your akonadi config/db, so should be a very last option.