[horde] Free/busy URL and Outlook 2013

[Bjoern Voigt]

Is it possible to configure the Horde global free/busy URL in
Outlook 2013?

At first I tried to setup a read-only or lookup free/busy URL like
described here

    "For some reason, Outlook 2013 doesn't use EAS to provide
    Free/Busy lookup, even though the version of the EAS protocol it
    uses supports it. If you want Outlook to be able to lookup
    Free/Busy information using Horde/Kronolith you need to provide
    it with the Free/Busy URL. Under /File -> Options -> Calendar
    Options/ select the "Free/Busy Options" button. Enter
    Kronolith's Free/Busy URL:
    http://example.com/horde/kronolith/fb.php?u=%NAME%. The %NAME%
    string will be replaced by the user portion of the SMTP mailing
    address used in the meeting request."
    (source: http://wiki.horde.org/ActiveSync)

(I use https instead of http with an official certificate for my
domain.)

Outlook didn't found any free/busy information. Outlook not even
tried to contact any URL on "example.com".

Later I tried to setup the same free/busy URL for publishing the
free/busy information too.

Now Outlook contacts my Apache server. I see this request once in my
Apache logs:

11.11.11.11 - - [02/Jul/2015:19:04:50 +0200] "OPTIONS
/horde/kronolith/fb.php?u=/o=ExchangeLabs/ou=Exchange%20Administrative%20Group%20(FYDIBOHF23SPDLT)/cn=Recipients
HTTP/1.1" 200 3751 "-" "Microsoft-WebDAV-MiniRedir/6.3.9600"

Of cause Horde replies only with empty useless free/busy information.

This is not what I want. I thought, Outlook should contact this
address https://example.com/horde/kronolith/fb.php?u=a_username if I
attempt to invite a_username at example.com.

Is there a bug in Kronolith or a configuration problem in my setup?

Greetings,
Björn