I'm almost sure iceowl didn't work with lowercase "http" last time I checked. Did you also check firefox/iceweasel? But since they're all using gecko it should work too.
I've successfully tested Firefox 3.0.5, Sunbird 0.9, and Thunderbird 0.9 with Lightning plugin, on a combination of WinXP 32-bit and MacOS 10.5.6. It also connects with iceweasel 3.0.6 on lenny.
I haven't tested iceowl 0.9, but only because the default package in lenny is still iceowl 0.8 (!) I can if that'd help.
In all cases, network.negotiate-auth.trusted-sspi is set to "https://<fqdn>" or "https://<fqdn1>,https://<fqdn2>".
-arthur. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org