[horde] annotations: Problems with Ingo - backend.php

[info@web-front.de]

Hello,

my problem is the DEFAULT variable in the procmail-script.

backends.php:
  'script' => 'procmail',
    'scriptparams' => array(
        // What path style does the IMAP server use ['mbox'|'maildir']?
        'path_style' => '',
        // An array of variables to append to every generated script.
        // Use if you need to set up specific environment variables.
        'variables' => array(
            // Example for the $PATH variable
            'PATH' => '/usr/bin',
            // Example for the $DEFAULT variable
            'DEFAULT' => '/var/mail/',
        )

How can I declare, that after the value /var/mail/ seems the "current logged in user" 
e.g.: /var/mail/user1

How can I fix it?

Kind Regards
Thomas