Dear Maintainer,

if (for instance) there is already a Maria DB account “axst”, a Horde account called
“axst” or even “Axst” can be created and the user can log in as usual but any attempt at
(for instance) creating a calendar entry results in a red box appearing in the right part
of the browser window reporting database integrity errors.

Other accounts work well, and the problematic account can also be deleted without problems.

It might help improve the situation to use some obfuscation like an internal prefix or
suffix to database account names created through Horde and check for existing accounts
before actually creating an account.