Describe the bug
Run-time fatal error.

To Reproduce

$ kmail

starts the program but results in a dialog that says

The Email program encountered a fatal error and will terminate now.
The error was:
Unable to obtain agent type ''.

Metadata
Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

Nixpkgs at d420c85

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute: `kmail`
# a list of nixos modules affected by the problem
module: