Thunderbird 2.0.0.23 & Norton Anti Spam & NIS10

Hi,

i found in my Thunderbirds Junk folder some e-mails marked with Norton AntiSpam.
I always thought, NIS10 does not support Thunderbird e.mail client, but does it mean, that all incoming mails will be checked by NIS10 for Junk Mails?
Thanks
Michael